Method and Apparatus for Guiding an External Needle to an Implantable Device

ABSTRACT

A system to generate a navigation field relative to an implanted device is disclosed. The system can include a small and/or thin localizer array positioned in the implanted device. A power management scheme and circuits can be provided to conserve and resource power in the implanted device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/317,553 filed on Mar. 25, 2010. The disclosure of theabove application is incorporated herein by reference.

FIELD

The present disclosure relates to a system for navigating an instrumentto a selected location, and more particularly to a method and apparatusfor guiding an external needle to an implantable medical device.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Implantable or implanted medical devices are often placed sub-dermallyin a body of a patient. The implanted medical device can be provided forvarious purposes, but include implanted infusion devices that includepumps. The pumps in the implanted medical devices infuse a material,such as a functional material or functional fluid into the patient. Thepump can be programmed to infuse the functional material at a selectedrate, based on a selected physiological sensing, etc. Over a period oftime, however, the reservoir in the implanted medical device may emptythus requiring the reservoir to be refilled to continue operation.

Refilling an implanted medical device requires accessing the reservoirof the implanted medical device. Accessing the reservoir, however, maybe difficult and require open access to the implanted device. Selecteddevices include ports through which a needle can be placed. The port canbe found through the dermis of the patient by palpation. Also, a HallEffect sensor can be used to determine the position of the port. Both ofthese methods, however, can lack the ability to determine theorientation of the refilling system relative to the implanted medicaldevice and the precise location of the port.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

A navigation system can determine precise orientation and position of adelivery system relative to an implanted or implantable medical device(IMD). The IMD can include a localizer formed of one or moretransmitting coils that transmit a navigation region or field. Anantenna can include one or tracking devices. The tracking devices can besensors. According to various embodiments, the sensors can include oneor more coils that can sense the field generated by the localizer in thenavigation region. The antenna can be associated with a support tooland/or a delivery container to determine the location of the supporttool and/or a delivery container. The location of the support tooland/or a delivery container can then be displayed on a display devicefor viewing by a user during a refilling procedure.

According to various embodiments, a system for generating a fieldrelative to an implanted medical device (IMD) may include a coil arraypositioned in the implanted medical device including a plurality ofcoils each having a winding group formed on a flexible circuit. The IMDcan include a single power source in the implanted medical device topower all components of the implanted medical device including the coilarray. A processor operable to energize the coil array according toselected instructions to assist in providing a substantially constantcurrent to the coil array may also be provided in the IMD. Each of theplurality of coils in the coil array is formed substantially thin in theflexible circuit to provide a substantially thin profile of the flexiblecircuit.

According to various embodiments, a method of operating a localizerassociated with an implanted medical device having a single power sourceto generate a navigation field and transmit telemetry from the implantedmedical device is disclosed. The method can include operating theimplanted medical device to deliver a therapy to a patient includingdrawing a current from the single power source. A stop signal can besent to a receiver in the implanted medical device to stop the operationof the implanted medical device from delivering the therapy. In responseto the stop signal, the operation of the implanted medical device can bestopped from delivering the therapy. After stopping operation of theimplanted medical device from delivering the therapy, a port finderroutine can be started having sub-routines including: starting a portfinder timer to time the operation of the port finder routine; andpowering a coil to emit a field; determining whether the port findertimer has expired. When it is determined that the port finder timer hasexpired, then operation of the implanted medical device to deliver thetherapy can be restarted.

According to various embodiments, a system to provide a constant currentto a localizer in an implanted medical device is disclosed. The systemcan include an operational amplifier operable to receive an inputvoltage and output a reference voltage to a precision resistor and afirst PMOS current mirror cascode. The system can further include a NMOScurrent mirror operable to receive an output voltage from the precisionresistor; a second PMOS current mirror cascode operable to receive anoutput voltage from the nmos current mirror and the first PMOS currentmirror cascode to output a substantially constant current based on theoutput reference voltage. A first coil, a first capacitor, and a firstswitch can be provided to form a connection between the second PMOScurrent mirror cascode and the first coil and the first capacitor. Thefirst capacitor is operable to tune the frequency of the output from thefirst coil to a selected frequency.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a schematic illustration of a navigation system and a deliverysystem according to various exemplary embodiments of the presentdisclosure;

FIG. 2 is an exploded perspective view of an implanted medical device;

FIG. 3 is an exploded schematic of a transmitter coil array;

FIG. 4 is an assembled view of a transmitter coil array with variousshaped coils;

FIG. 5 is a schematic of a tuning control circuit;

FIG. 5A is a schematic of a tuning control circuit;

FIG. 6 is a flowchart of a power management protocol;

FIG. 7 is a schematic of a constant current circuit to power atransmitter coil array;

FIG. 8 is a schematic of an antenna array;

FIG. 9 is an environmental schematic view of an antenna and atransmitter coil array;

FIG. 10 is an exploded, perspective view of a support tool of thedelivery system according to various exemplary embodiments of thepresent disclosure;

FIG. 11 is an exploded view of the support tool of FIG. 10;

FIG. 12 is a section view of the support tool of FIG. 10;

FIG. 13 is a section view of the support tool of FIG. 10;

FIG. 14 is an exploded, perspective view of the support tool accordingto additional exemplary embodiments of the present disclosure;

FIG. 15 is an exploded, perspective view of the support tool accordingto additional exemplary embodiments of the present disclosure;

FIG. 16 is an exemplary view of a display device according to variousexemplary embodiments of the present disclosure;

FIG. 17 is an exemplary view of the display device communicating aninverted or flipped condition of the implantable device according tovarious exemplary embodiments of the present disclosure;

FIG. 18 is an exemplary view of the display device communicating agraphical image associated with a calibration process according tovarious exemplary embodiments of the present disclosure;

FIG. 19 is an exemplary view of the display device communicating generalguidance information according to various exemplary embodiments of thepresent disclosure;

FIG. 20 is an exemplary view of the display device communicatingdetailed guidance information according to various exemplary embodimentsof the present disclosure;

FIG. 21 is another exemplary view of the display device communicatingdetailed guidance information according to various exemplary embodimentsof the present disclosure;

FIG. 22 is another exemplary view of the display device communicatingdetailed guidance information according to various exemplary embodimentsof the present disclosure;

FIG. 23 is another exemplary view of the display device communicatingdetailed guidance information according to various exemplary embodimentsof the present disclosure;

FIG. 24 is an illustration of an exemplary procedure according tovarious exemplary embodiments of the present disclosure;

FIG. 25 is a top view of a support tool according to various otherexemplary embodiments of the present disclosure;

FIG. 26 is a side view of a supply assembly according to various otherexemplary embodiments of the present disclosure; and

FIG. 27 is a side view of a supply assembly according to various otherexemplary embodiments of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

The following description of various embodiments is merely exemplary innature and is in no way intended to limit the teachings, itsapplication, or uses. By way of example, the following description isdirected toward a delivery system for delivering a functional fluid toan implantable device, such as an implantable infusion device. It isappreciated, however, that the following may be used for other systemswithout departing from the scope of the present disclosure.

I. Introduction

FIG. 1 schematically illustrates a navigation system 10 according tovarious exemplary embodiments of the present disclosure. The navigationsystem 10 can include a processor system 12 as discussed further herein.Exemplary navigation systems include those disclosed in U.S. Pat. No.7,366,562, issued on Apr. 29, 2008 to John H. Dukesherer et al. and U.S.Pat. App. Pub No. 2008/0132909, published Jun. 5, 2008, to Bradley A.Jascob et al., both incorporated herein by reference. Commercialnavigation systems include the StealthStation® AxiEM™ SurgicalNavigation System sold by Medtronic Navigation, Inc. having a place ofbusiness in Louisville, Colo., USA. Generally, the processor system 12can be a controller that includes one or more processors (e.g. processorcores), either in a single box or a container, or in several containers.

The processor system 12 can process an image for display on a displaydevice 14 and receive and transmit information regarding a location,where location information can include both x, y, and z position androll, pitch, and yaw orientation information, of a tracking device 20associated with a tracked instrument 61 (including those discussedhereinbelow) relative to a localizer 22. Accordingly, six degree offreedom (6 DOF) information can be determined with a tracking ornavigation system. The localizer 22 can be used to determine a locationof the tracking device 20 and, in turn, the location of the trackedinstrument 61 can be determined relative to the localizer based on thetracked location of the tracking device 20. The localizer 22 can beassociated with a device implanted in a patient 16, which can bereferred to as an implanted or implantable medical device (IMD) 30.

In various embodiments, the tracking device 20 has an antenna orreceiving coil array 24 that receives or senses information from thelocalizer 22. The localizer 22 can include a transmit coil array thattransmits or emits a field, such as an electromagnetic field, that canbe sensed by the antenna 24 of the tracking device 20. According tovarious embodiments, it will be understood that the antenna 24 of thetracking device 20 can also be powered to transmit a field that isreceived by the localizer 22. Thus, the tracking device 20 can beoperated to transmit or receive a signal and the localizer 22 canoperate to do the opposite of the tracking device 20.

FIG. 1 also schematically illustrates a delivery system 28. In someembodiments, the delivery system 28 can include a supply assembly 50(including a container and a hypodermic needle or the like). Thedelivery system 28 can also include a support tool or guide 60. As willbe discussed, the delivery system 28 can be used for delivering afunctional fluid from outside the patient 16 to a the IMD 30 that isimplanted within the patient 16. Also, the support tool 60 can be usedfor stabilizing and guiding the supply assembly 50 relative to thepatient 16 during use.

The tracking device 20 can be operably coupled to the support tool 60 oralternatively to the supply assembly 50. For instance, in the embodimentof FIG. 1, the tracking device 20 can be operably coupled to the supporttool 60 to allow the support tool 60 to be tracked (i.e., the supporttool 60 can be the tracked instrument 61). In other embodiments, thetracking device 20″ (shown in phantom) can be operably coupled to thesupply assembly 50 to allow the supply assembly 50 to be tracked (i.e.,the supply assembly 50 can be the tracked instrument 61″). As such, thenavigation system 10 can be used to detect the location of the trackedinstrument 61, 61″ of the delivery system 28. This can facilitatedelivery of the functional fluid from the delivery system 28 to the IMD30, as will be discussed in greater detail below.

In some embodiments, the implantable device 30 can include a port 32 anda reservoir 34. The port 32 can define an insertion axis X, and the port32 can be located entirely within the patient 16 (e.g., beneath thepatients dermis or skin). Also, the port 32 can be in fluidcommunication with the reservoir 34. Functional fluid from the deliverysystem 28 can be delivered to the reservoir 34 via the port 32. Oncedelivered, the implantable device 30 can supply the patient 16 with thefunctional fluid on a predetermined basis or as needed basis. Forinstance, the IMD 30 can be an implantable infusion device, and thefunctional fluid within the reservoir 34 can be any appropriate fluid,such as an analgesic, insulin, insulin substitute, hormone treatment, orany other appropriate treatment. The IMD 30 can pump the functionalfluid to predetermined tissue of the patient 16 according to apredetermined schedule to maintain the health, pain control, or otherphysiological features of the patient 16. The IMD 30 can also functionto deliver the therapy based on sensed physiology of the patient 16.Exemplary embodiments of the implantable device 30 include the infusionsystems SYNCHROMED® II Drug Infusion System, Models 8637-20, 8637-40,SYNCHROMED® EL Drug Infusion System, Model 8627, ISOMED® Constant FlowInfusion System, Models 8472-20, 8472-35, 8472-60 sold by Medtronic,Inc. having a place of business in Minneapolis, Minn., USA.

The IMD 30 may also include a pumping system and connections to allowfor pumping of the functional material from the reservoir 34 to thepatient 16 as required. Further, the IMD 30 can include a processor andmemory portions with programming for delivering the functional fluid tothe patient 16 at a selected time and rate and for other programmedoperations. As the functional fluid is evacuated from the reservoir 34,the reservoir 34 may be refilled at selected times using the deliverysystem 28 and the navigation system 10.

II. Implanted Medical Device Coil Array/Localizer

With reference to FIG. 1, and additional reference to FIG. 2, the IMD 30can include several portions assembled within a casing 2010 that can beclosed with a top lid or top casing 2012. The top casing 2012 can definethe port 32 through which the delivery system 28 can be used to fill thereservoir 34. The reservoir 34 is defined within the casing 2010 and canbe filled with the appropriate functional fluid. The reservoir 34 can beclosed with a top cap or top portion 2014. A septum or internal port2016 can be defined by the internal cap 2014.

The implanted medical device 30 can house various components that arenecessary or selected for operation of the implanted medical device 30.For example, a pump 2018 can be positioned on the top plate 2014.Interconnected or positioned relative to the top plate 2014 can also bea first printed circuit board (PCB) 2020. The printed circuit board caninclude various circuitry, including an internal or implanted medicaldevice processor 2022. It will be understood that other circuitry canalso be included with the internal (PCB) 2020, but the processor 2022can be used to execute selected instructions that can be stored in amemory that is also on the internal (PCB) 2020 and/or can also beincluded with the processor 2022. The processor 2022 can be one or moreappropriate processors that are selected and used in various implantedmedical devices such as the implanted medical device infusion systemsdisclosed above and, sold by Medtronic, Inc., having a place of businessin Minneapolis, Minn.

Also included within the implanted medical device 30 can be a powersource, such as a battery 2024 that is used to power the variouscomponents of the implanted medical device 30, including the pump 2018and the processor 2022. The battery 2024 can also be used to power thetransmitter coil array (as discussed herein) of the localizer 22 that isprinted or etched onto a second printed circuit board 2026. The secondPCB 2026 can also be referred to as the localizer or coil array PCB2026, herein. The power source can include only one or a plurality ofbatteries or other chargeable and power storage systems (e.g.capacitors). Including a single battery, however, can allow a moreefficient power and component design.

The top casing 2012 can be sealed to the body casing 2010 to enclose allof the components of the IMD 30 prior to implantation in the patient 16.As is understood by one skilled in the art, the coil array PCB 2026 canbe used to transmit or receive data as a part of a telemetry system toeither program or receive data from the internal processor 2022, storeinformation in an internal memory system or retrieve information from aninternal memory system, or any other appropriate task relative to theIMD 30. It will also be understood that the IMD 30 may also include anadditional antenna in addition to the coil array PCB 2026 for telemetrypurposes. Additional antennas, such as a telemetry antenna can be formedon an exterior of the case top 2012. The telemetry system can be used tocommunicate with the processor 12 of the navigation system 10 or with aseparate programmer 2027 that can be used to program the delivery of thefunctional material from the IMD 30 or sensed physiological events.

According to various embodiments, however, the single battery 2024 canbe used to power all of the components and portions of the IMD 30. Thesingle battery or other power supply can power the pump 2018, theprocessor 2022, the localizer 22, and other various components that mayrequire power during the life cycle of the 30. Accordingly, it can beselected to provide a power conserving system, as discussed herein.

With a continued reference to FIG. 2 and additional reference to FIG. 3,the coil array PCB 2026 is illustrated. The coil array PCB 2026 can beformed by layering a plurality of portions to form a PCB or flex circuit2026. The coil array PCB 2026, as illustrated in the exploded view inFIG. 3, can include a far side or bottom layer 2030. The bottom layer orfar side 2030 can be the layer that is positioned closest to theinternal top plate 2014 in the implanted medical device 30. The bottomlayer 2030 can be formed of appropriate materials, such as polyimide.The bottom layer 2030 can include coil array areas 2032, 2034 and 2036,onto which the coil arrays, or at least a portion of the coil arrays,can be positioned, as discussed further herein. The coil array areas2032-2036, are open areas that can be filled with the coil arraymaterial. The bottom layer 2030 can also include an opening or a passage2038 that extends from the external port 32 to the internal port 2016.Accordingly, the passage 2038 substantially defines the target or areathrough which a piercing member 4058 may pass to fill the reservoir 34of the implanted medical device.

A first portion or first layer of the coil array 2040 can be formeddirectly on the bottom layer in the coil array areas 2032-2036. Thefirst coil array portion 2040 can include three coils or coil partsincluding a first coil 2042, a second coil 2044, and a third coil 2046.These coils 2042-2046 can be respectively positioned on the bottom layer2030 in the respective positions 2032, 2034, and 2036. The coils2042-2046 can be formed by appropriate mechanisms including copperdeposition methods onto the bottom layer 2030. It will be understoodthat the coils 2042-2046 can be formed by other mechanisms includingetching, thin wire coiling, deposition (including vacuum, vapor,sputtering), and other appropriate mechanisms or techniques. The coils2042-2046 can be formed as continuous lengths or spirals of conductivematerial, such as the copper, on the bottom layer 2030. The coils2042-2046 can be formed to include a selected number of turns to achievean appropriate field strength when powered or a current is driventhrough the coils 2042-2046. The field strength can be selected by thecurrent per conductive path, the number of conductive paths, and thegeometry of the conductive paths. For example where the geometries areconvex, the area enclosed by the conductive paths can select the fieldstrength. Thus, the field strength can be augmented by selection ofturns and the number of coil portions, as discussed below.

In addition, the width of the coils or traces of the coil can beselected to achieve the selected number of turns. The number of turns inthe coils 2042-2046 can include about 10 turns to about 100 turns,including about 35 turns to about 45 turns, and further including about38 turns to about 42 turns. The number of turns can be selected toachieve a proper density of coil turns in the coil array or select afield strength, including about 38 turns to 42 turns of a trace or wirehaving a selected thickness. The thickness of the traces or wire can beselected to be about 0.001 inches (in.) (about 0.025 millimeters (mm) toabout 0.01 in. (about 0.25 mm) including about 0.0019 in. (about 0.0483mm) to about 0.008 in. (about 0.203 mm). The two ends of each of thecoils 2042-2046 can terminate in terminal portions 2050. The terminalportions can be positioned near vias or passages in an insulation orisolation layer 2056. The isolation layer 2056 can be an appropriatematerial, such as a polyimide that can isolate the first coil portion2040 from a second coil portion 2060. The isolation layer 2056 insulatesor isolates the coils 2042-2046 of the first coil array portion 2040from the second coil array portion 2060 including the coil parts 2062,2064, and 2066. Thus, the first coil array portion 2040 does not shortto the second coil array portion 2060.

The second coil array portion 2060 can also include three coils or coilparts 2062, 2064, and 2066 formed as lengths of material generallyforming spirals. The coils 2062-2066 of the second coil array portion2060 can be positioned over or relative to the isolation layer 2056 incoil areas 2058 a, 2058 b, and 2058 c. The coils 2062-2066 can be formedon the isolation layer 2056 in a manner substantially similar to formingthe first coil array portion 2040 on the bottom layer 2030. Accordingly,the coils 2062-2066 of the second coil array portion 2060 can be formedby copper deposition, etching, thin wire coiling, or the like.Additionally, the number of turns in the coils 2062-2066 or the secondcoil array portion 2060 can also be selected to be the same, a largernumber, or smaller number, than the coils in the first coil arrayportion 2040. Generally, the coils are selected to include an identicalnumber of turns in the coils 2042-2046 of the first coil array portion2040 to the respective coils 2062-2066 in the second coil array portion2060. The second coil array portion 2016 generally overlays and issubstantially identical to the coils in the first coil array portion2040 with the isolation layer 2056 separating the two.

Vias through the isolation layer 2056 allow connection of the terminalportions 2050 of each of the first coils 2042-2046 of the first coilarray portion 2040 to connect with terminal portions 2068 of each of thecoil parts of the second coil array portion 2060 such that the firstcoil 2042 of the first coil array portion 2040 is in series and will actsubstantially as a single coil with the first coil portion 2062 of thesecond coil array portion 2060. Likewise for the other respective coilparts 2044 and 2064 and coil parts 2046 and 2066 form second and thirdcoils of the localizer 22. Each of the coils 2042-2046 of the first coilarray portion 2040 are in series with a single one of the respectivecoils 2062-2066 of the second coil array portion 2060 such that each ofthe coil part pairs act as a single coil. Accordingly, the localizer 22can be formed of the two coil array portions 2040, 2060, but cansubstantially include three coils including a first coil formed by thecombination of the coil parts 2042 and 2046, a second coil formed of thecombination of the coil portions 2044 and 2064, and a third coil formedof the combination of the coil portions 2046 and 2066. It will beunderstood, additional coil array portions can be formed by includingmore coils that are separated with additional isolation layers to allowthe three, four, or more coil array portions. Furthermore, only one coilarray portion can be selected.

As discussed further herein, the first coil array portion 2040 and thesecond coil array portion 2060 can be powered by the battery 2024 totransmit or form the navigation field, including an electromagneticfield, relative to the IMD 30. The three coils of the localizer 22,discussed herein can be defined by the coil part pairs described above.Including the localizer 22 in the IMD 30 allows for a compact andcontained navigation system 10 that may not require an externallocalizer to track the tracking device 20 and the IMD 30 to navigate thesupply system 28 relative to the IMD 30.

The coil array PCB 2026 can further include a top layer 2070 and astiffener portion 2072. All of the portions, including the bottom layer2030, the first coil array portion 2040, the isolation layer 2056, thesecond coil array portion 2060, the top layer 2070, and the stiffener2072 can be formed together as a single flex circuit or the coil arrayPCB 2026. The single flex circuit of the PCB 2026 can be positionedwithin the IMD 30. The single PCB 2026 can be formed to have a thicknessfrom the outside of the bottom layer 2030 to the outside of the toplayer 2072 to be about 0.01 in. to about 0.03 in., including about0.0128 in. (about 0.325 millimeters (mm)) to about 0.0249 in. (about0.63246 mm). This thickness allows the PCB 2026 to be contained withinthe IMD 30 without increasing or substantially increasing the size ofgenerally available IMDs 30. Thus, the IMD 30 can be comfortablypositioned in the patient 16 while providing the navigation localizer 22in the IMD 30.

As illustrated in FIG. 3, it will be understood that the coils of thecoil array portions 2040, 2060 can be formed to be substantially annularor ovoid (generally oval) in exterior dimension or shape. As discussedabove, the traces of the coils can be a spiral on coil array PCB 2026.It will be understood that it can be selected to form the tracings orconductive portions of the coils to be substantially thin to form asubstantially thin construction, including the dimensions discussedabove. Nevertheless, the shape of the coils can also be formed inselected shapes. For example, as illustrated in FIG. 4, a coil array PCB2026 can include substantially elliptical coils 2074, “lima bean shaped”coils 2076, or circular coils or cylindrical coils 2078. By providingthe coils in different shapes, substantially all the area of the coilarray PCB 2026′ can be covered with tracings that define coils of thelocalizer 22. However, including the coils to be substantiallycylindrical or ovoid, can allow for the formation of a substantiallyuniform field with a minimum resistance in the coil tracings to achievethe appropriate field. As discussed further herein, the coil arrays ofthe localizer 22 formed on the coil array PCB 2026 can be used togenerate the field that is sensed or received by the antenna 24 todetermine a position of the delivery system 28 relative to the implantedmedical device 30.

With reference to FIG. 5, a tuning circuit 2080 can be included on thecoil array PCB 2026 or the first internal PCB 2020 that can be used tocontrol power consumption or tuning of the various components of the IMD30. For example, the coil array of the localizer 22 can be powered atselected times to emit or generate the navigation field relative to theIMD 30. Alternatively, or in addition thereto, other portions can bepowered to transmit telemetry data from the IMD 30. For example, atelemetry antenna 2081 can transmit a signal from the IMD 30 and can beformed in the implanted medical device 30, such as integrated in theexterior of the case 2010 or the top case 2012.

The telemetry system of the IMD 30 can operate at a selected frequency,such as about 125 (kHz). The frequency of the telemetry system can beused to transmit data regarding the IMD 30 to the processor 12 or othersystems for programming the IMD 30. The coil arrays for the localizer22, however, can be operated at other selected frequencies. For example,the coil arrays of the localizer 22 can be operated at about 40 to 50kHz, including about 45 kHz; and further including about 10 kHz to about50 kHz, including about 25 kHz. Accordingly, the frequency of the signaltransmitted from the telemetry system may generally not interfere withthe signal transmitted from the localizer 22. Nevertheless, it may beselected to transmit a signal to the telemetry system using the coils ofthe localizer 22 formed on the coil array PCB 2026. For example,transmitting a signal using the coils on the coil array PCB 2026 can bea back-up or in addition to transmitting telemetry without otherantennas formed on the IMD 30. The use of the localizer 22 as atelemetry antenna can be done with time multiplexing techniques and thetuning circuitry 2080.

Accordingly, the tuning circuit 2080 can be provided with the IMD 30,for example on the coil array PCB 2026 or the internal PCB 2020. Thetuning circuit 2080 can tune a driving signal to any one of the selectedcoils (e.g. formed of the coil parts). As discussed herein, a first coilC1 can exemplary include the coil formed of the coil parts 2042, 2062 inthe tuning circuit 2080. It will be understood that the coil C1 can beany of the coils formed in the coil array of the localizer 22 and thecoil C1 is merely exemplary. The signal driven into the tuning circuitry2080 can be from a telemetry receiver 2082 or a localizer transmitdriver 2084. The two drivers 2082, 2084 can be positioned within the IMD30, such as on the first printed circuit board 2020.

The localizer transmit driver 2084 can be used to find the port 32 ofthe IMD 30, therefore it can also be referred to as an electronic portfinder (EPF) or port finder (PF). Accordingly, it will be understoodthat discussion herein of PF can be limited to the discussion of thenavigation system 10 for finding or navigating the delivery system 28 tothe port 32 of the IMD 30. Accordingly, the localizer driver 2084 canalso be referred to as the PF transmit driver 2084.

The tuning circuit 2080 can include a tuning control or switch 2086 toswitch the incoming current to oscillate through both a telemetryfrequency tuning capacitor 2088 and an EPF frequency tuning capacitor2090 or just the telemetry tuning capacitor 2088 and the coil C1. Inother words, when the switch 2086 is active the tuning circuit 2080 willbe an LC circuit including the EPF tuning capacitor 2090, the telemetrytuning capacitor 2088, and the coil C1. When the switch 2086 isinactive, the tuning circuit 2080 can be a LC circuit of only thetelemetry tuning capacitor 2088 and the coil C1. The circuitry can alsobe grounded to ground 2092 such as to an exterior of the case 2010.

When the switch 2086 is active, the circuit 2080 can generate theappropriate frequency for the EPF. When the switch 2086 is inactive thetuning circuit 2080 can generate a frequency for the telemetry system.The switch can be activated depending upon the time and which of thetelemetry receiver 2082 or the localizer transmit driver 2084 is beingused. The signal, from the respective drivers 2082, 2084, can be tunedto the appropriate frequency for the telemetry or the EPF system of thelocalizer 22 depending upon the selected feature or signal to betransmitted from the IMD 30 by the coil C1 of the localizer 22.

It can be selected, however, to achieve or attempt to achieve a maximumcurrent through the coil C1 (or any appropriate coil). Accordingly,components in the tuning circuit 2080, according to various embodimentsincluding those discussed herein, can be selected or varied (e.g. acapacitance of a capacitor or an inductance of the coil C1) to achieve aselected current through the coil C1. A maximum current through the EPFcoils can generate a maximum field for the navigation or guiding of thesupply assembly 50 relative to the IMD 30.

As exemplary illustrated in FIG. 5, when the tuning circuit 2080 istuned to the telemetry frequency, the telemetry frequency tuningcapacitor 2088 can be charged to power the coil C1 to transmit a signalfrom the coil C1 at the telemetry frequency. Alternatively, if the EPFis selected to be used, the switch 2086 can charge the EPF frequencytuning capacitor 2090 and the telemetry frequency tuning capacitor 2088to power the coil C1 at the frequency for the navigation system 10.Accordingly, the tuning circuit 2080 can be used to selectively tune thecoils of the localizer 22 to an appropriate frequency for either thetelemetry or the EPF systems in a time multiplexing manner. As discussedabove, the EPF can include navigating the delivery system 28 with thenavigation system 10. It is understood, however, as illustrated inphantom in FIG. 5, the switch 2086, the telemetry tuning capacitor 2088,and the telemetry receiver 2082 need not be provided in the same tuningcircuit with the EPF coils, as discussed further herein.

The tuning circuitry 2080 can be provided for each of the coils of thelocalizer 22. The coils can include the coil C1 mentioned above, asecond coil C2 formed of the coil parts 2044, 2064, and a third coil C3formed of the coil parts 2046, 2066. Accordingly, all of the coils ofthe localizer 22 can be tuned to transmit the signal at the selectedfrequency.

It will be understood that if a single one of the tuning circuit 2080 isused to drive each of the coils of the localizer 22, one or moreswitches can be provided between the tuning circuit 2080 and each of thecoils. The switches (not illustrated) can individually and selectivelyallow driving each of the coils of the localizer 22 at the selectedtuned frequency individually and alternatively at a selected time.Accordingly, it can be selected to provide switches as opposed to aplurality of the tuning circuits. As discussed herein, each of the coilscan be placed in parallel with the tuning capacitors to drive each ofthe coils separately at the selected frequency.

It will be further understood, that additional and/or separate coils,such as the telemetry antenna 2081, illustrated in FIG. 5A, can beprovided for the telemetry system that are separated from the EPF systemand EPF coils C1, C2, and C3. As illustrated in FIG. 5A, a separatetuning circuit including the tuning capacitor 2088, which may include adifferent capacitance than when in parallel with the EPF tuningcapacitor 2090, can be used when driving the telemetry antenna 2081.Also, the telemetry antenna 2081, the telemetry tuning capacitor 2088,and related connections can be placed in any appropriate location, suchas the PCB 2020, of the IMD 30. Thus, providing a single tuning circuitand including one or more capacitors and switches for both the EPFsystem and the telemetry is not required. The coils C1, C2, and C3(including the coil parts 2042, 2044, 2046, 2062, 2064, and 2066)therefore can be selected to be used with only the EPF system.

In an example where the tuning circuit 2080 includes only the EPF coils(as illustrated in solid lines in FIG. 5), a capacitor can be selectedthat does not achieve an ideal circuit resonance frequency, but can beselected for achieving a selected current through the coil or a maximumcurrent through the coil C1 based on the input voltage. Generally, thetuning circuit 2080 can include the tuning capacitor 2090 and the coilC1 that is an inductor. A Q-factor can be determined for the tuningcircuit 2080 and can be used in determining components to maximizecurrent through the coils C1. While the inductance of the coil C1 may beselectively fixed, the capacitance can be altered to achieve a selectedcurrent though the coil C1.

As discussed above, the EPF frequency can include about 25 kHz. Usingcoil inductance and the target tuning frequency of about 25 kHz theresultant capacitance for resonance is about 2.2 micro-Farads (uF). Thecalculated resonant frequency, however, may not maximize current throughthe EPF coils. A high current through the coil C1, it was discovered, isachieved by tuning the circuit to a higher resonant frequency, such asto about 30 kHz to about 50 kHz, including about 40 kHz, with a 1.0 uFcapacitor. It was discovered that the 1.0 uF capacitor actuallyincreases a current through the EPF coils at the 25 Khz operationalfrequency relative to the tuned circuit with a 2.2 uF capacitor.

In an implanted application, capacitor aging may theoretically decreasethe capacitance value of a capacitor by about 15% over 8 years of use.Thus, current changes in the EPF coils over a selected 8 year time spanmay change about 1% to about 3% when using a 1.0 uF capacitor and about10% to about 20% when using a 2.2 uF capacitor. The tuning circuit 2080including the 1.0 uF capacitor includes a reduced current variationthrough the coils C1 due to capacitor aging relative to the 2.2 uFcapacitor. A higher resonant frequency capacitor, relative to operatingfrequencies, was discovered to increase current through the EPF coils(to maximize field strength with the EPF coils). Also, high resonantfrequency capacitors can decrease current variance over a selectedlifespan of the capacitor in the tuning circuit 2080, including a changeof less than about 3%, including less than about 2%.

Again, it is understood that such a tuning circuit can include only asingle capacitor or capacitor system with no switch and used to onlytune the EPF coils. Further, maintaining a selected current through thecoils assists in tracking or navigating the instrument with the EPF coilsystem by assisting in maintaining a constant or high field strengthover the life span of the system. It will be understood, however, thatsimilar principles may be applied to an antenna system for the telemetryas well.

In reference to FIG. 6, the IMD 30 includes a battery 2024 that canpower all of the components of the IMD 30. However, it can be selectedto power portions of the IMD 30 separately or substantially sequentiallyto achieve selected results. For example, having the battery powermultiple components substantially simultaneously can form or allowvoltage variations and/or current variations that can be unselected orresult in noisy transmissions. Accordingly, providing a power managementscheme, as illustrated in a flowchart 2100, can allow for sequentialpowering or interleaving of powering of components of the IMD 30 toachieve all of power savings, power management, and reduced noise orconstant amplitude alternating current and/or voltage from the battery2024. The power management scheme can be implemented as instructionsthat are executed by a processor in the IMD 30, including the processor2022, or can be executed and sent to the IMD 30 with the telemetry ofeither the navigation processor 12 or the programmer 2027.

With reference to flowchart 2100, it can start in start block 2102 whichcan lead to a request to start port finder in block 2104. The request tostart the port finder block 2104 can come from the processor 12 or anyappropriate portion of the navigation system 10. For example, thedelivery system 28 can transmit a signal through the antenna 24 to thetelemetry system of the IMD 30 to instigate or to request the start portfinder in block 2104. Alternatively, the telemetry system, which can beprovided with a programmer, can be used to send the request start portfinder signal in block 2104. A signal transmitted from a system that isseparate from the navigation system 10 can also send a signal to thenavigation system 10 to begin receiving at the antenna 24 the signalfrom the localizer 22 within the implanted medical device 30.Accordingly, the request start port finder block 2104 can send a signalto the implanted medical device 30 to begin the electronic port finderpower management diagram 2100 and also to the navigation system 10 tobegin receiving and analyzing a signal for navigating and determining alocation of the port 32 of the implanted medical device 30.

After the request start port finder is received by the IMD 30, a signalto block high current devices and other features of the IMD, such asturning off the pump 2018, can be done in block 2106 as discussed above,the IMD 30 can include a processor 2022 that, upon receiving the requestport finder signal block 2104, can perform the remainder of the blocksof the algorithm illustrated in the flow charts 2100. That is, the flowchart 2100 can include steps of an algorithm that are executed by theprocessor 2022 to achieve the interleaving and power management in theflow chart 2100. The instructions for the algorithm can be stored on thememory included with the processor 2022 or another memory on the circuitboards, including the first circuit board 2020 or the coil array PCB2026.

Once the high current devices, or other devices other than the poweringof the localizer 22, are turned off the EPF on timer can be started inblock 2108. The length of the EPF on-timer can be any appropriate amountof time, such as one to thirty seconds, or as long as selected toachieve appropriate navigation of the delivery device 28 to the port 32.The EPF on-timer can determine that the number of iterations of poweringthe coils of the localizer, as illustrated, in the flow chart 2100 willbe cycled through to achieve port finding with the delivery system 28.In addition, it will be understood that a second or other additionalrequest to start the port finder can be sent to the IMD 30 after the EPFon-timer has run for at least one cycle.

A coil one-timer can be started in block 2110. The coil timer can be setfor a selected amount of time, such as about 100 milliseconds, includingabout 50 to about 200 milliseconds. Once the coil one-timer is startedin block 2110, coil 1 can be turned on in block 2112. As discussedabove, coil 1 as illustrated in the flow chart 2100 can include the coilparts 2042 and 2062. The flow chart 2100 will also reference coil 2 andcoil 3 which can respectively include the coil parts 2044, 2064 and thecoil parts 2046, 2066. Accordingly, coils 1, 2, and 3 referenced in theflow chart 2100 refer to the coil trace pairs discussed in relation toFIG. 3.

In turning on coil 1, coil 1 can be powered at the selected tunedfrequency, as discussed in relation to FIG. 5. Coil 1 can be powered toemit a signal or field for navigating the delivery system 28 relative tothe IMD 30. When powering the coil 1, the coil 1 can generate anelectromagnetic field that can be sensed with the antenna 24 of thedelivery system 28. As discussed further herein, this can allownavigation of the delivery system 28 relative to the IMD 30 to find theport 32 with a hypodermic needle 4058. In navigating, the antenna 24 ofthe tracking device can operate similar to tracking devices as disclosedin U.S. Patents and Patent Application Publications incorporated byreference above. By navigating the delivery system 28 to the IMD 30 alocation, as discussed above, can be determined of the delivery system28 relative to the IMD 30 to identify when the hypodermic needle 4058 isat an appropriate location for piercing the port 32. As discussedfurther herein, the display 14 of the navigation system 10 can be usedto illustrate the delivery system 28 relative to the implanted medicaldevice 30 including the port 32. Accordingly, the coil 1, and the othercoils 2 and 3 sequentially or simultaneously can generate the field fornavigating to the delivery system 28.

Once the coil 1 is powered in block 2112, a decision block 2114 ofwhether the coil 1 timer has expired can be made. If the decision is no,then a no path 2116 can be followed to continue powering the coil 1 inblock 2112. If the timer has expired, a yes path 2118 can be followed toturn off coil 1 in block 2120. Once coil 1 is turned off, a gap timercan be started in block 2122.

The gap timer 2122 can be selected to be an appropriate time. Theappropriate time can be selected to assist in distinguishing between thevarious coils of the localizer 22. The gap between powering coilsdetermined by the gap timer can be about 10 to 100 millisecondsincluding about 50 milliseconds. Accordingly, a distinguishing gapbetween receiving the fields from the respective coils, including coil1, 2, and 3, and can be used to help identify the position of the coils,the position of the port 32, and which coil or if an alternative coil isbeing received. Once the gap timer is started in block 2122, a decisionblock of whether the gap timer has expired in 2124 can be accessed. Ifthe gap timer has not expired then a no path 2126 can be followed tocontinue the gap timer. Alternatively, if the gap timer has expired,then a yes path 2128 can be followed to start the coil 2 timer in block2130.

Once the coil 2 timer has started in block 2130 coil 2 can be turned onin block 2132. As discussed above, the coil timer in block 2130 can bean appropriate length that is selected for the system and can includethe same time length for the coil 1 timer. In operating coil 2, stepsthat are substantially similar to those for operating coil 1 arefollowed and will be discussed briefly here. Following coil 2, coil 3 isalso operated and those steps can also be substantially similar to stepsfor coils 1 and 2 and will be discussed only briefly following here.

Once coil 2 is turned on then a decision block 2134 can be used todetermine whether the coil 2 timer has expired. If the coil 2 timer hasnot expired a no path 2136 can be followed to continue powering coil 2.Alternatively, if the coil timer has expired then a yes path 2138 can befollowed to turn off coil 2 and block 2140. Again, once the coil 2 isturned off then a gap timer can be started in block 2142.

Once the gap timer has been started a decision block 2144 can be used todetermine whether the gap timer has expired. If the gap timer has notexpired then a no path 2146 can be followed to continue the gap timer.Alternatively, if the gap timer has expired then a yes path 2148 can befollowed to start the coil 3 timer in block 2150. Once the coil 3 timerhas started, the coil 3 can be turned on in block 2152. Followingpowering the coil 3 in block 2152 a decision block 2154 of whether thecoil 3 timer has expired can be used. If the coil 3 timer has notexpired a no path 2156 can be followed to continue powering coil 3.Alternatively, if the coil 3 timer has expired then a yes path 2158 canbe followed to turn off coil 3 in block 2160.

Once coil 3 has been turned off in block 2160 all three of the coils ofthe localizer 22 have been powered in sequence or in a time multiplex ordivision manner. Circuitry for powering the coils will be discussed indetail herein and can be used to substantially sequentially power thecoils at substantially identical frequencies. Such time multiplexing canbe used to transmit three different fields from the three differentcoils from the IMD 30. It will be understood, however, that differentfrequencies for each of the three coils can also be used to allowsubstantially powering them simultaneously. Powering the three coils ofthe localizer 22 simultaneously, however, can require greater powerconsumption from the battery 2024 and may not be selected. However, itwill be understood that frequency multiplexing, allowing all of thethree coils to be powered substantially simultaneously at the localizer22 can be used.

Once the third coil is turned off in block 2160, however, the decisionblock of whether the port finder request is still active can be accessedin block 2162. If the port finder request is no longer active then a nopath 2164 can be followed to exit the interleaving or EPF powermanagement in block 2166. In exiting the power management in block 2166other high current devices or other portions of the IMD 30 can berepowered. Additionally, it will be understood that an additional orfurther requests can be made even if the current EPF request, determinedby the EPF timer is no longer active.

If the decision block of the port finder request in block 2162 is stillactive, then a yes path 2168 can be followed to start a blank timer inblock 2170. The blank timer can be selected to be an appropriate length,which can be about 50 to 150 milliseconds, including about 100milliseconds. The blank timer 2170 can be at a different length than thegap timer between each of the coils to assist in identifying when thethird coil has been powered and when the first coil will be powerednext. Accordingly, the length that the gap timer in block 2170 can beused to assist in identifying when a complete cycle of powering allthree coils has been completed. The length of the gap timer in block2170, therefore, can be programmed and saved with the navigation system10 to assist in determining when all three coils have been powered.

Once the blank timer has been started in block 2170, a decision block ofwhether the blank timer has expired in block 2172 can be accessed. Ifthe blank timer has not expired, a no path 2174 can be followed tocontinue the blank timer block 2170. Alternatively, if the blank timerhas expired, then a yes path 2176 can be followed to a decision block ofwhether the EPF on-timer has expired in block 2178. If the decision thatthe EPF on-timer has not expired then a no path 2180 can be followed tostart the coil 1 timer again in block 2110. If the decision is that theEPF on-timer has expired then a yes path 2182 can be followed to enablethe high current devices in block 2184 that were blocked or turned offin block 2106. These can include powering the pump 2018, the telemetrysystem, or other system of the implanted medical device 30.

After the high current devices are enabled in block 2184 an EPFoff-timer can be started in block 2186. Once the EPF off-timer isstarted, a decision block 2188 can determine whether the EPF off-timerhas expired. If the EPF timer has not expired in block 2188 then a nopath 2190 can be followed to continue the EPF off-timer and block 2186.However, if it is determined that the EPF off-timer has expired, then ayes path 2192 can be followed to a new decision block of whether a portfinder request is still active in block 2194.

As discussed above, additional EPF active requests can be made evenafter a first EPF request has been made. Accordingly, a second requestcan be made after the EPF off-timer has been turned on in block 2186. Ifan additional request has been made in the decision block in 2194, a yespath 2196 can be followed to again block or maintain blocking the highcurrent devices in block 2106 and the EPF power management flow diagram2100 can be followed again. Alternatively, if no additional port finderrequest has been made a no path 2198 can be followed to an exitinterleaving block 2166. Accordingly, the flow diagram 2100 can be usedto manage power and selectively power different components of the IMD30, including the localizer 22, separately from other high currentdevices, including the pump 2018 or the telemetry system of the IMD 30.Accordingly, the power management flow chart 2100 can be used, eitheralone or in combination with other electric circuitry systems, toprovide substantially constant amplitude alternating current and/orvoltage to the localizer 22. By providing substantially constantamplitude alternating current and/or voltage to the localizer 22, thelocalizer 22 can be used to generate a field that is substantially knownand selected for allowing navigation of the delivery system 28 relativeto the port 32 of the IMD 30.

With reference to FIG. 7, a constant amplitude alternating currentand/or voltage circuit 2300 illustrates connections of variouscomponents of the IMD 30 including the localizer 22 and the battery orpower source 2024. The current can be a substantially constant amplitudealternating current. A substantially constant amplitude alternatingcurrent can generally vary by about 1% to about 3%, including about 1%,and further including less than about 1%. As illustrated in the circuit2300, a voltage signal from a battery 2302 can be input into the circuit2300 and be switched to power or drive each of the three coils, herereferenced as coil 1-2304, coil 2-2306 and coil 3-2308. As discussedabove, each of the coils can be provided in parallel with respectivetuning capacitors including a first turning capacitor 2310, a secondtuning capacitor 2312, and a third tuning capacitor 2314. It will beunderstood, however, as discussed above regarding the tuning circuitry,a single tuning capacitor could be provided in the system and multipleswitches can be used to switch between each of the coils 2304-2308.

The reference voltage signal is applied to an operational amplifier (OPAmp) 2320 which then outputs a reference voltage to aresistor/transistor loop including a precision resistor 2322, a NMOS(e.g. a n-type transistor) transistor current mirror 2324, and a PMOS(e.g. a p-type transistor) mirror cascode 1 2326. The precision resistor2322 can be external to components on an integrated circuit. Theintegrated circuit can include the OP Amp 2320, the PMOS mirror cascode1 2326, a PMOS mirror cascode 2 2330 and the NMOS transistor currentmirror 2324. The precision resistor 2322 can be substantially precisehaving a variance of less than about 1 percent. Additionally, the NMOStransistor current mirror 2324 can multiply a reference current by about4 times as it is transmitted to the PMOS (e.g. p-type transistor) mirrorcascode 2 2330. The PMOS mirror cascade 2 2330, along with the NMOScurrent mirror 2324, and the PMOS mirror cascode 1 2326 can includetransistors to convert the reference voltage to a reference current thatis substantially constant that is output through outputs 2332 from thePMOS mirror cascode 2 2330. The substantially constant amplitudealternating current and/or voltage can be held to vary by about 1% toabout 3%, including about 1% or less, and further including asubstantially immeasurable variance (e.g. a variance that is within anerror of measurement).

The substantially constant amplitude alternating current and/or voltageis transmitted to the coils 2304-2308 through a plurality of respectiveswitches. A first switch 2334 can be provided in series with the firstcoil 2304, a second switch 2336 can be provided in series with thesecond coil 2306, and a third switch 2338 can be provided in series withthe third coil 2308. Additionally, as briefly mentioned above,additional switches, including three additional switches can be providedto switch the current between a single capacitor and each of the coils2304-2308, as understood by one skilled in the art.

A signal can be provided to each of the respective switches 2334-2338 toactivate the switches 2334-2338 to drive the respective coils 2304-2308.Separate control signals can be transmitted from a first PMOS switchcontrol signal 2340, a second PMOS switch control signal 2342 and thethird PMOS switch control signal 2344 to separately activate each of thethree switches 2334-2338. Providing the plurality of switches 2334-2338and the plurality of control signals 2340-2344 can allow for each of thecoils 2304-2308 to be substantially independently and sequentially, orin any appropriate order, driven for generating the signal from thecoils 2304-2308 of the localizer 22 for navigation of the deliverysystem 28.

The components of the respective portions of the circuit 2300, includingthe PMOS mirror cascodes and the NMOS current mirrors can be selectedtransistors to amplify and generate the substantially constant amplitudealternating current and/or voltage to the plurality of switches2334-2338. Additionally, the switches 2334-2338 can be PMOS switchesthat are provided to switch the current to the coils 2304-2308alternatively, for example, according to the power management flow chart2100. In addition, the switches can be modulated to assist in tuning thefrequency of the current to the coils 2304-2308. For example, asdiscussed above, the frequency for transmission from the coils 2304-2308can be about 25 kHz or about 45 kHz.

III. Receiving Coil Array/Antenna Configuration

The coils of the coil array PCB 2026 can generate a field that is sensedby the antenna 24 of the tracking device. With reference to FIG. 8, theantenna portion 24 of the tracking device 20 can include one or aplurality of coils. The plurality of coils of the antenna 24 can form areceiving antenna array 24. The plurality of coils can be arrayed toreceive a signal transmitted by the localizer 22 discussed above.

With reference to FIG. 8, the antenna array 24 can include a pluralityof tracking devices. The tracking devices can include one or more coils.In various embodiments, the tracking devices can include a plurality ofcoils formed as a group, or a coil group. Each coil group can have aselected number of coils, including three coils that have a singleorigin 3000. Each of the coils is positioned along an x, y, and z axis3002, 3004, and 3006, respectively.

The coils positioned around the center 3000 can be wound substantiallyor tightly around the single center 3000 or, alternatively, coiled toform cylinders as illustrated in alternative detail 3010 along therespective axes 3002, 3004, 3006. Accordingly, three coils arepositioned around the center 3000 can form a coil group 3020. Theantenna 24 can include four substantially identical coil groupsincluding the first coil group 3020, a second coil group 3022, a thirdcoil group 3024 and a fourth coil group 3026.

Generally, each of the coils of the coil groups 3020-3026 are wound orformed orthogonal to one another. Thus, each of the coils can determineor sense separate the field in the in the orthogonal axes and generateseparate signals based on the sensed field. The separate signals fromeach of the coils can then be used to determine the location informationregarding the location of the coil groups 3020-3026. Each of the coilgroups 3020-3026 can then generally determine complete locationinformation regarding the individual coil group 3020-3026.

Each of the coil groups 3020-3026 can be positioned substantially at thevertices of a tetrahedron 3030, as illustrated in FIG. 8. Thetetrahedron can be a regular or an irregular tetrahedron. For example,the tetrahedron defined by the four coil groups can be a regulartetrahedron where the tetrahedron has substantially equal length legs orsides. Each side or leg of the tetrahedron 3030 can be about eightmillimeters (mm) to about 15 mm, including about 11 mm to 14 mm, andfurther including about 12.5 mm. The volume of the tetrahedron,therefore, is about 200 millimeters cubed (mm³) to about 300 mm³,including about 250 mm³. The coil groups 3020-3026 can be positioned inthe tetrahedron array such that the antenna 24 includes twelve discretecoils that are formed in the tetrahedron to receive or sense the field,such as an EM field, generated by the localizer 22. It will beunderstood, however, that the coil groups can be formed into a selectedregular or irregular geometric shape. As discussed above, however, thetetrahedron configuration can achieve a selected confidence in sensingthe EM field generated by the localizer 22.

With reference to FIG. 9, the localizer 22 incorporated in the IMD 30can include the coils on the coil PCB 2026 is illustrated by the topcoils 2062-2066. The coils 2062-2066 as illustrated here and in the Figsabove, are generally positioned around the area of the port 32. It canbe selected to place the coils at a selected spacing or substantiallyevenly spaced apart. These coils 2062-2066, when powered as discussedabove, can generate a navigation field that is or can include the EMfield that can be generated or emitted into the space surrounding by theIMD 30 as illustrated by the hemispherical region 3040, generally aroundthe port 32 as well. It will be understood that the navigation region3040 can be divided into various navigation zones, as discussed furtherherein, relative to the implanted medical device 30. In addition, thenavigation region 3040 can be any appropriate shape formed by thelocalizer 22 relative to the implanted medical device 30. For example,the components or materials of the implanted medical device 30 canaffect the shape of the field that forms the navigation region 3040. Asillustrated, however, the substantially planar shape of the coils of thelocalizer 22 in the implanted medical device 30 can form a substantiallyspherical or hemispherical navigation region relative to the port 32 ofthe implanted medical device 30. Also, the coils 2062-2066 can generatea small or weak portion of a field 3042, which may be smaller or weakerthan the general navigation field 3040, that extends to an under orbottom side 31 of the IMD 30. The smaller field portion 3042 can be usedto determine the orientation of the IMD 30 relative to the antenna 24,as discussed herein.

Once the antenna 24 is positioned within the navigation region 3040 ofthe implanted medical device 30, the position of the antenna 24 can bedetermined with the navigation system 10, including the processor 12.The tracking device 20 can communicate via wires or wirelessly with theprocessor 12. Similarly, the processor 12 can communicate wirelessly orvia wires with the localizer 22 of the IMD 30. Various transmissionsystems are discussed in the patents and applications incorporatedherein by reference and via the systems discussed above. Further, theprogrammer 2027 can transmit via wires or wirelessly with the navigationsystem 10 and with the IMD 30.

The determination of the location of the antenna 24 can be based uponnavigation techniques by determining the sensed field in each of thecoils of the coil groups 3020-3026 in the antenna array 24. Because eachof the coil groups 3020-3026 includes three coils that are positionedsubstantially orthogonal to each other (e.g. one along each of the threedimensions of space) in the navigation region 3040 substantially alllocation information can be determined. By providing the four coilgroups at spaced positions from one another along the legs 3030 of thetetrahedron, a three-dimensional location, including X-Y-Z spatialcoordinates and orientation of each of the coil groups 3020-3026 can bedetermined. Each of the coil groups 3020-3026 can then be interpolatedor the information can be used to determine the position of the portionof the tetrahedron defined by the coil groups 3020-3026 of the antenna24. The position can then be illustrated on the display 14 as discussedfurther herein to provide information to a user for moving the deliverysystem 28 to the port 32.

The localizer 22, including the plurality of coils formed by the coilparts 2042, 2062; 2044, 2064; and 2046, 2066 that generate thenavigation region 3040 and the antenna 24 including the coil groups3020-3026, can be used to guide the delivery system 28 to the port 32 ofthe IMD 30. As discussed briefly above, and in further detail herein,the antenna 24 associated with the delivery system 28 can be used alonewith the localizer 22 incorporated into the IMD 30 to navigate thedelivery system 28 to the IMD 30 for filling the reservoir 34 of the IMD30. Accordingly, the localizer 22, incorporated in the IMD 30 and theantenna 24 included with the delivery system 28, can be used to providea substantially mobile and discrete system that can be used to fill thereservoir 34 by navigating the needle 4058 to the port 32. For example,the delivery system 28, as discussed further herein, can be a portablesystem that includes the navigation processor 12, display 14, and theantenna 24 that can be used in a Doctor's office or other substantiallynon-surgical outpatient or clinical setting. This allows for filling thereservoir 34 of the IMD 30 without requiring large or complex externalnavigation systems to identify the location of the port 32 and therelative position of the delivery system 28 for filling the reservoir34.

It will be further understood that the antenna 24 can be operated togenerate a field that is sensed with the coils of the localizer 22 inthe IMD 30. Thus, rather than the localizer 22 generating the EM field3040 in the navigation space, the localizer 22 can sense an EM fieldbeing generated by the antenna array 24. Otherwise, the navigationsystem can be operated in a similar manner to power the coils of thelocalizer 22 to receive the EM field generated by the antenna 24.

IV. Supply System and Support Guide

The delivery system 28 can be a substantially efficient system todeliver the functional fluid to the reservoir 34 of the IMD 30. Thetracking device 20 can be associated with the delivery system 28 toallow navigation of the delivery system 28 relative to the IMD 30.Because the IMD 30 has been implanted in the patient 16 for a period oftime, the delivery system 28 can be navigated to the precise location ofthe port 32 using the tracking device 20. As discussed above and asshown in FIG. 1, the tracking device 20″ can be operably coupled to thesupply assembly 50 such that supply assembly 50 is the trackedinstrument 61″, and/or the tracking device 20 can be operably coupled tothe support tool 60 such that the support tool 60 is the trackedinstrument 61.

Referring now to FIGS. 1 and 10-13, the delivery system 28 will bediscussed in greater detail. As shown in FIGS. 1, 12, and 13, the supplyassembly 50 can incorporate various features of a commercially availablehypodermic needle or syringe. As such, the supply assembly 50 caninclude a hollow container 4054 with a curved outer surface 4056 (e.g.,three dimensionally curved outer surface 4056). The supply assembly 50can also include a piercing member 4058 or needle that is elongate andthat has a sharpened distal tip 4059 for piercing the skin of thepatient 16. The piercing member 4058 can define a longitudinal axis X′(i.e., a supply axis), and a lumen (not shown) can extend longitudinallyfrom the container 4054 and axially through the piercing member 4058.The supply assembly 50 can also include a plunger (not shown) that ismoveably coupled to the container 4054 to be manually or automaticallyactuated by the user in order to force the functional fluid from thesupply assembly 50. Thus, as will be discussed, when in a targetposition relative to the port 32 of the implantable device 30, thepiercing member 4058 can pierce the skin 4041 of the patient 16 (FIG.13) to be received by the port 32, and the functional fluid can bedelivered from the supply assembly 50 to the reservoir 34 of theimplantable device 30.

In other embodiments illustrated in FIGS. 26 and 27, the container 4054can be operably coupled to a supply line 4057 (e.g., a tube or hose) onone end. The supply line 4057 can supply the functional fluid throughthe container 4054 to the piercing member 4058. Accordingly, thefunctional fluid can be delivered conveniently by pumping the functionalfluid through the supply line 4057.

Referring now to FIGS. 1, 10 and 11, the support or guide tool 60 willbe discussed in greater detail. As shown, the support tool 60 can besubstantially flat and thin and can be made out of a rigid material,such as a polymeric material. The support tool 60 can include a supportmember 4062 and a handle 4064. The handle 4064 can be elongate and canbe sized such that the user can grasp and support the handle 4064 withone hand or with a few fingers. The support member 4062 can be widerthan the handle 4064, and the handle 4064 can extend away from thesupport member 4062.

The support member 4062 can include a main body 4063 and a removablemember 4065 (FIGS. 10-13). The main body 4063 can be integrallyconnected to the handle 4064 so as to be monolithic. The removablemember 4065 can be removably attached to the main body 4063 as will bediscussed in greater detail below.

The support member 4062 can also include an opening 4066 with an axis X″(FIGS. 12 and 13). As shown in FIGS. 12 and 13, the opening 4066 can becooperatively defined by both the main body 4063 and the removablemember 4065. As will be discussed in greater detail below, the opening4066 can receive the supply assembly 50 (FIGS. 12 and 13), and thesupport member 4062 (i.e., both the main body 4063 and the removablemember 4065) can support the supply assembly 50 such that the axis X′ ofthe supply assembly 50 remains substantially fixed relative to the axisX″ of the support member 4062. In some embodiments, the support member4062 can support the supply assembly 50 such that the axis X′ of thesupply assembly 50 remains substantially aligned with and fixed relativeto both the axis X″ of the support member 4062 and the axis X of theport 32. Accordingly, the support member 4062 can hold the supplyassembly 50 with the axes X, X′, X″ substantially aligned to ensure thatthe supply assembly 50 engages the port 32 as will be discussed.

As shown in FIG. 10, the main body 4063 can include an outer edge 4070and an elongate slot 4072 that extends from the outer edge 4070. As willbe discussed, the slot 4072 defines a portion of the opening 4066 thatreceives the supply assembly 50. Also, as shown in FIG. 11, the mainbody 4063 can include grooves 4074 recessed on inner surfaces 4073 ofthe slot 4072. The grooves 4074 can extend substantially parallel to theslot 4072.

Also, as shown in FIG. 11, the removable member 4065 can be generallycruciform in shape so as to include tongues 4076 extending from oppositesides of the removable member 4065. Each of the tongues 4076 can beslideably received within respective ones of the grooves 4074 so as toremovably attach the removable member 4065 to the main body 4063.Accordingly, the removable member 4065 can be removably attached to themain body 4063 via a tongue and groove coupling.

It will be appreciated that the tongues 4076 could be included on themain body 4063, and the grooves 4074 could be included on the removablemember 4065 without departing from the scope of the present disclosure.It will further be appreciated that the removable member 4065 could beremovably attached to the main body 4063 via any other suitablecoupling. For instance, the removable member 4065 could be attached viaa break-away coupling. More specifically, the tongues 4076 could befixed within the respective grooves 4074, and in order to remove theremovable member 4065 from the main body 4063, the user can fracture andbreak the tongues 4076 away from the removable member 4065 by hand.

As shown in FIG. 11, the removable member 4065 can also include aprojection 4078 that is received in a corresponding recess 4080 (shownin phantom) on the main body 4063. The projection 4078 can be a nub ofraised material that is located on one or more of the tongues 4076, andthe recess 4080 can be included within one or more of the grooves 4074.However, it will be appreciated that the projection 4078 can be includedon the main body 4063, and the recess 4080 can be included on theremovable member 4065. The projection 4078 can be received within therecess 4080 in order to retain the removable member 4065 in asubstantially fixed position relative to the main body 4063. Forinstance, as the tongues 4076 advance into the respective grooves 4074,the projection 4078 can eventually snap into the recess 4080 tosubstantially lock the removable member 4065 in a fixed position. Thus,the position of the removable member 4065 relative to the main body 4063can be ensured.

As shown in FIGS. 12 and 13, the main body 4063 and the removable member4065 can each include a nesting surface 4082 a, 4082 b. With the nestingsurfaces 4082 a, 4082 b, the removable member 4065 and the main body4063 can cooperatively support the supply assembly 50. Morespecifically, the nesting surfaces 4082 a, 4082 b can be threedimensionally contoured so as to substantially conform in shape andcontour with the corresponding outer surface 4056 of the supply assembly50. The nesting surfaces 4082 a, 4082 b can each include an upperportion 4084 a, 4084 b and a lower portion 4086 a, 4086 b (FIG. 13). Theupper portions 4084 a, 4084 b can be recessed deeper than the lowerportions 4086 a, 4086 b. Also, the upper portions 4084 a, 4084 b can bethree-dimensionally contoured, and the lower portion 4086 a, 4086 b canbe two-dimensionally contoured.

Thus, when the supply assembly 50 is inserted into the opening 4066(FIG. 13), the upper portions 4084 a, 4084 b can closely abut and nestagainst the outer surface 4056 of the container 4054 of the supplyassembly 50. Also, the lower portions 4086 a, 4086 b can closely abutand nest against the piercing member 4058.

Such nesting maintains alignment between the axis X′ of the supplyassembly 50 and the axis X″ of the opening 4066 of the support tool 60,and the support tool 60 can help the user to maintain the supplyassembly 50 in its target alignment relative to the axis X of the port32 of the implantable device 30. For instance, the support tool 60 canlimit rotational movement of the axis X′ of the supply assembly 50relative to axes Y, Z as shown in FIG. 13.

It will be appreciated that the nesting between the supply assembly 50and the support tool 60 can be especially effective because the opening4066 is substantially continuous so as to extend substantiallycontinuously about the axis X′ of the supply assembly 50. Morespecifically, the main body 4063 and the removable member 4065 (and thenesting surfaces 4082 a, 4082 b) cooperate to substantially completelysurround the supply assembly 50 for ensuring alignment between the axesX, X′, X. However, it will be appreciated that the opening 4066 could bediscontinuous (e.g., the removable member 4065 might not be included andthe notch 4072 would remain open) without departing from the scope ofthe present disclosure.

As stated, the lower portion 4086 a, 4086 b of the nesting surfaces 4082a, 4082 b closely conform in shape to the piercing member 4058 of thesupply assembly 50. For instance, the lower portions 4086 a, 4086 b canbe spaced apart substantially equal to the diameter of the piercingmember 4058. As such, even when the container 4054 of the supplyassembly 50 is spaced from the upper portion 4084 a, 4084 b of thenesting surfaces 4082 a, 4082 b (FIG. 12), the lower portion 4086 a,4086 b of the nesting surfaces 4082 a, 4082 b can maintain alignmentbetween the axis X′ of the supply assembly 50 and the axis X″ of theopening 4066 of the support tool 60. Thus, for instance, if the port 32of the implantable device 30 is just below the surface of the skin 4041,the supply assembly 50 can pierce shallowly through the skin 4041, andthe support tool 60 can maintain the supply assembly 50 in its targetalignment.

Once the supply assembly 50 has engaged the port 32 of the implantabledevice 30 (FIGS. 12 and 13), the removable member 4065 can beselectively removed from the main body 4063 as discussed above. Then,the main body 4063 can be moved away from the patient 16 while thesupply assembly 50 remains in a substantially fixed position relative tothe patient 16 (i.e., remains engaged with the port 32). Morespecifically, by removing the removable member 4065, the main body 4063can move away from the patient until the supply assembly 50 is fullyoutside the slot 4072. Then, the support tool 60 can be re-used foranother patient 16, or the support tool 60 can be discarded.

In some embodiments, the support tool 60 can be packaged with theremovable member 4065 already attached to the main body 4063. However,in other embodiments, the support tool 60 and the removable member 4065can be packaged separately. Moreover, the supply assembly 50 and thesupport tool 60 can be packaged together or separately. Additionally, insome embodiments, the member 4065 is not removable and is insteadintegrally connected to the main body 4063 so as to be monolithic.

Referring now to FIG. 10, the tracking device 20 of the navigationsystem 10 will be discussed in greater detail. The tracking device 20can include one or more antennae 24 that are housed within a housing4090. The housing 4090 can be operably coupled to the support tool 60 ata known position and orientation relative to the opening 4066 and theaxis X″ of the opening 4066. Thus, the navigation system 10 cancommunicate with the antennae 24 and the localizer 22 (FIG. 1) in orderto detect the location of the axis X″ of the opening 4066 relative tothe axis X of the port 32 of the implantable device 30. Since thesupport tool 60 maintains the axis X′ of the supply assembly 50 inalignment with the axis X″ of the opening 4066, the tracking device 20can detect the location and orientation of the axis X′ of the supplyassembly 50 relative to the axis X of the port 32.

As shown in FIG. 10, the tracking device 20 can be removably coupled tothe support tool 60. For instance, the housing 4090 of the trackingdevice 20 can be removably coupled to the handle 4064 on an end oppositethe support member 4062. In some embodiments, the housing 4090 and thehandle 4064 are coupled via a one-way coupling. More specifically, thehousing 4090 can include a first recess 4091 and a second recess 4092,and the first recess 4091 can be larger in diameter than the secondrecess 4092. Also, the handle 4064 can include a first projection 4093and a second projection 4094, which correspond in size and which arereceived in the first and second recesses 4091, 4092, respectively.Accordingly, the tracking device 20 can be keyed to the handle 4064 andattached to the handle 4064 in only one relative orientation, therebyensuring that the antenna 24 is at a known position/orientation relativeto the opening 4066 and the supply assembly 50.

The tracking device 20 can further include a retainer clip 4095 thatextends around the housing 4090 and removably attaches to the handle4064 of the support tool 60. The retainer clip 4095 can include one ormore recesses 4096 that receive corresponding projections 4097 includedon the handle 4064 of the support tool 60. As such, the retainer clip4095 can further secure the housing 4090 to the handle 4064, and theposition/orientation of the antenna 24 relative to the opening 4066 andsupply assembly 50 can be further ensured.

In other embodiments illustrated in FIG. 25, the tracking device 20 canbe integrally or removably coupled to main body 4063 of the support tool60. As shown, the antenna 24 can be disposed about the axis X″ (e.g., ina tetrahedral configuration) and adjacent the opening 4066. The trackingdevice 20 can be coupled in any suitable manner, including the means ofattachment described above with respect to FIG. 10.

It will be appreciated that because the tracking device 20 is removablyattached to the support tool 60, the tracking device 20 can be usedmultiple times with multiple patients 16. This can produce cost savingsbecause the relatively expensive tracking device 20 can be re-used whilethe less expensive support member 4062 and handle 4064 can be discarded.Also, there is a reduced chance of cross contamination between patients16 because the support member 4062 and handle 4064 can be used a singletime on one patient 16. This becomes important since the support member4062 and the handle 4064 are likely to contact the skin 4041 and becomecontaminated by blood, tissue, germs, etc.

Also, because the support tool 60 is tracked, the support tool 60 can beused for other purposes. For instance, the support tool 60 can usedwhile preparing to supply the functional fluid, independent of thesupply assembly 50. The support tool 60 can be laid against the patient16 to find the position of the support tool 60 relative to the port 32of the IMD 30. Also, as will be discussed in greater detail below, thisinformation can be used to automatically detect and indicate the type ofpiercing member 4058 needed for supplying the functional fluid to theport 32. For instance, with the detected position of the support tool 60relative to the port 32, the system can detect the necessary length ofthe piercing member 4058, etc.

Moreover, as mentioned above, the tracking device 20″ (shown in phantomin FIG. 1 and in solid lines in FIGS. 26 and 27) can be operably coupleddirectly to the supply assembly 50 at a known location relative to thedistal tip 4059 of the piercing member 4058. For instance, as shown inFIG. 26, the tracking device 20″ can be removably coupled to thecontainer 4054 of the supply assembly 50. Also, as shown in FIG. 26, thetracking device 20″ can include antenna 24 that are disposed about thesupply axis X′ (e.g., in a tetrahedral configuration). In otherembodiments shown in FIG. 27, the tracking device 20″ can be removablycoupled to the container 4054 of the supply assembly 50 (e.g., via aLuer Lock connection or via any other suitable connection) such that thetracking device 20″ is disposed entirely on one side of the supply axisX′. Also, in some embodiments, the tracking device 20″ can be keyed tothe supply assembly 50 such that the tracking device 20″ is at a knownorientation relative to the supply assembly 50 when attached thereto. Inother embodiments, the tracking device 20″ can be integrally coupled tothe supply assembly 50.

It will be appreciated that the tracking device 20″ can be coupled tothe supply assembly 50 in any suitable location and in any suitablemanner. Furthermore, it will be appreciated that the tracking device 20″can be coupled to the supply assembly 50 as disclosed in U.S. PatentApplication Publication No. 2009/0082782, published Mar. 26, 2009, toScott Kalpin, which is incorporated herein by reference in its entirety.

Thus, in some embodiments, the distal tip 4059 of the piercing member4058 can be tracked independent of the support tool 60. Also, where thetracking device 20″ is removably coupled to the supply assembly 50, thesupply assembly 50 (or at least the piercing member 4058) can be usedonce and discarded, and the more expensive tracking device 20″ can beremoved from the supply assembly 50 for repeated use.

Furthermore, in some embodiments, the tracking device 20″ can be coupledto the container 4054 of the supply assembly 50 and used independent ofthe piercing member 4058. For instance, the tracking device 20″ candetect the relative position of the container 4054 relative to the port32 of the IMD 30. Then, as will be discussed below, the system canautomatically detect the length of the piercing member 4058 necessary toreach the port 32.

As shown in FIG. 14, the support tool 60′ can also include aprophylactic member 4098. The prophylactic member 4098 can be made outof any suitable material, such as a substantially rigid polymer. Theprophylactic member 4098 can include a base 4099 and a wall 4081 thatextends from an outer edge of the base 4099. The prophylactic member4098 can also be forked so as to have a shape substantially similar tothe support member 4062′. The prophylactic member 4098 can also includeone or more projections 4083 that extend from an interior portion of thebase 4099 in the same direction as the wall 4081.

The projections 4083 can be removably received within correspondingrecesses 4085 formed in a bottom surface 4087 of the support member4062′. In some embodiments, the projections 4083 can be held within therecesses 4085 via a frictional fit. In other embodiments, theprojections 4083 can be held within the recesses 4085 via aninterference fit. It will also be appreciated that the support member4062′ can include the projections 4083 while the prophylactic member4098 can include the recesses 4085.

When attached, the base 4099 can cover the bottom surface 4087 of thesupport member 4062′, and the wall 4081 can cover the outer edge 4070′and the inner surface 4073′ of the support member 4062′. Also, duringuse, the prophylactic member 4098 can be disposed between the supportmember 4062′ and the patient to thereby reduce the likelihood ofcontamination of the support member 4062′. Moreover, the prophylacticmember 4098 can be disposed between the supply assembly (not shown inFIG. 14) and the support member 4062′. Also, although a removable member4065 of the type shown in FIG. 10 is not shown in FIG. 14, theprophylactic member 4098 can be shaped so as to fit over the removablemember 4065 as well.

Thus, the support tool 60′ can be sterilized and used multiple timeswith multiple different patients because contamination of the supportmember 4062′ is unlikely. Also, the prophylactic member 4098 can bediscarded after use, and a new, sterile prophylactic member 4098 can beused for each patient. Thus, the prophylactic member 4098 can be usefulin cases where the tracking device 20′ is fixedly attached to thesupport tool 60′. However, it will be appreciated that the prophylacticmember 4098 can be used in cases where the tracking device 20′ isremovably attached as well.

Referring now to FIG. 15, another embodiment of the prophylactic member4098″ is illustrated. In the embodiment shown, the prophylactic member4098″ includes a glove portion 4089 with an opening 4079. The gloveportion 4089 can be made out of any suitable material, such as arelatively thin layer of flexible and elastic polymeric material. Theopening 4079 can be sized so as to receive the support member 4062″ suchthat the support member 4062″ can be disposed in an interior space 4075of the prophylactic member 4098″.

Accordingly, during use, the support member 4062″ can be substantiallyenclosed within the interior space 4075 of the prophylactic member4098″, and the prophylactic member 4098″ can act as a barrier betweenthe patient and the support member 4062″ as well as a barrier betweenthe supply assembly (not shown in FIG. 15) and the support member 4062″.Thus, the prophylactic member 4098″ can reduce the likelihood ofcontamination of the support member 4062″.

V. Navigation Display

The localizer 22 and the tracking device 20, as discussed above, can beprovided in the IMD 30 and the delivery system 28, respectively, toallow navigation of the delivery system 28 relative to the port 32 ofthe IMD 30. Once navigated the delivery system 28 can be used to deliverthe functional fluid to the reservoir 34 of the IMD 30. The display 14of the navigation system 10 can be used to graphically display arendered image illustrating the determined location of the deliverysystem 28 either alone or with information relating to the position ofthe IMD 30.

Referring now to FIGS. 16-24, a system and method for displayingguidance or navigation information and navigating the tracked instrument61, 61″ will now be discussed in greater detail according to variousembodiments of the present disclosure. As discussed above, thenavigation system 10 can detect the location of the tracked instrument61, 61″ relative to the implantable device 30. For instance, thenavigation system 10 can detect the location of the port 32 and/or theinsertion axis X relative to the tracked instrument 61, 61″, and withthis information, the user can more easily locate tracked instrument 61,61″ relative to the port 32 for delivering the functional fluid to thereservoir 34. To facilitate navigation of the tracked instrument 61,61″, the processor system 12 can cooperate with the tracked instrument61, 61″, implantable device 30 and display device 14 to provide guidanceinformation as well as an interactive user interface, as will bedescribed in greater detail below. The following discussion willcontinue to make reference to the tracked instrument 61, 61″, where, asdiscussed above, the tracked instrument 61 can include support tool 60with operably coupled tracking device 20 and supply assembly 50, and thetracked instrument 61″ can include supply assembly 50 with the removablycoupled tracking device 20″.

Typically, a medical practitioner, such as a nurse or clinician(hereinafter referred to as a “user”), can palpate the patient 16 todetermine a general or approximate location of the implantable device 30to be filled with the functional fluid. After determining theapproximate location, the user can use the navigation system 10 toprovide general and detailed guidance information to navigate thetracked instrument 61, 61″ to the location of the port 32. Thenavigation system 10 can be a portable system where processor system 12and display device 14 are incorporated therein for portable use, or canbe a permanent or semi-permanent system incorporated into a facilityroom or on a movable workstation (not shown).

The display device 14 can include an image area or graphical display5010 for displaying guidance information and receiving user input, aswell as a menu or instruction area or areas 5014 that can be used todisplay various instructions, menus, prompts and the like forcommunicating with and receiving input from the user via the processor12. The user can turn on or initialize the navigation system, upon whichthe processor system 12 can cooperate with the display device 14 to showthe imageable area 5010 and instruction area 5014, as generally shown inFIG. 16. Once initialized, the display device 14 can prompt the user toselect from a preconfigured menu of various implantable devices 30.

As the navigation system 10 can be used with various implantable devices30, selection of a certain implantable device 30 can be used to uploadspecific information related to that specific device, including but notlimited to, a graphical illustration of the device, calibrationinformation, port 32 location relative to the localizer 22, and a numberof ports in the pump as well as the function of each port. For example,and with reference to an implantable device 30 having multiple ports,the exemplary implantable device 30 can be configured with two ports 32,shown as 32 and 32′ in FIG. 16, where port 32 can be used to fillreservoir 34 as previously discussed, and port 32′ can be use for directinjection of the functional fluid to a portion of the anatomy.

In an alternative configuration, the display device 14 can beautomatically initialized using the telemetry system discussed above. Inthis configuration, data regarding the implantable device 30, such asmodel, number of ports, calibration data, etc. can be communicated tothe processor system 12 and display device 14 using the telemetry systemsuch that the user would not need to initialize the system and selectthe implantable device model.

If an implantable device 30 model is selected by the user orcommunicated by the telemetry system that includes multiple ports, theprocessor system 12 can display the multiple ports on display device 14and prompt the user to select a target port (i.e., port 32 or 32′) fornavigation thereto, via port selection prompts 5022. The selected targetport 32 or 32′ can be identified on display device 14 with a graphicalrepresentation, such as ring 5026. Once an implantable device model isselected and a target port is selected, if applicable, the view of theimage area can be centered on the selected target port and a viewdirection of the image area can be parallel to the insertion axis X ofthe target port, as shown in FIGS. 16-23. In this manner, the view shownon the image area 5010 can be perpendicular to the insertion axis X ofport 32 such that axis X is normal to the paper in FIGS. 16-17.

Ring 5026 can be illustrated with a specific color and size todifferentiate ring 5026 from other guidance rings that will be discussedin greater detail below. It should also be appreciated that ring 5026can be illustrated in various geometric patterns or configurationssuitable to visually identify the selected target port 32 or 32′. Once aport is selected, such as port 32 in FIG. 16, the processor system candisplay a cross-hair configuration 5030 with a graphical representationof an origin or target location 5032 over the selected port 32, as shownfor example in FIG. 16. For discussion purposes, port 32 willhereinafter be referred to as the selected or target port 32.

Upon initializing the navigation system 10 and selecting an implantabledevice model, the user can calibrate the display device 14 to theorientation of the implantable device 30 in patient 16, as well as tothe movement of the tracked instrument 61, 61″. As the specificorientation of the implantable device 30 within patient 16 may not beknown, the calibration process can correlate or register the orientationof the implantable device 30 relative to the display and to movement ofthe tracked instrument 61, 61″. This can be accomplished using thelocalizer 22 in the implantable device 30 and the respective trackingdevice 20, 20″ associated with the respective tracked instrument 61,61″.

For example, in one exemplary embodiment shown in FIG. 18, the processorsystem 12 can display a series of three spaced apart calibration points5034, 5038 and 5042 in a triangular configuration, and prompt the userto direct the tracked instrument 61, 61″ to point 5034, then point 5038,and finally point 5042. Upon directing the tracked instrument 61, 61″ toeach point, the user can provide an indication to the processor system12 that the tracked instrument 61, 61″ is adjacent the respectivecalibration point. In this manner, based on a known relationship ofpoints 5034-5042, movement of the tracked instrument 61, 61″ can beregistered to the image area 5010.

As the navigation system 10 is being initialized, the processor system12 can be configured to determine if the implantable device 30 is out ofposition such that it is flipped over or inverted inside patient 16relative to where the user would be attempting to insert the piercingmember or needle 4058 into patient 16 towards device 30. The navigationfield from the localizer 22 can extend around the implantable device 30such that the field strength can vary in a predetermined manner relativeto a front side 5046 of the implantable device 30 having the target port32 and an opposite, back side 5050. In this manner, if implantabledevice 30 is flipped over or inverted, the field strength sensed by thetracking device 20, 20″ associated with the tracked instrument 61, 61″can be lower and below a predetermined threshold as compared to thefield strength if the front side 5046 was orientated towards theexpected anterior or posterior side of the patient, as generally shownin FIG. 1.

If it is determined that there is a flipped or inverted implantabledevice condition, the processor system 12 can be configured to displayan exemplary graphical indication 5054 in the image area 5010 to alertthe user of such a condition upon initialization of the system, as shownin FIG. 17. While FIG. 17 shows graphical indication 5054 as displaying“PUMP FLIPPED”, it should be appreciated that various other graphicalindications can be used to illustrate or convey to the user that theimplantable device 30 is inverted or flipped over. The processor system12 can be configured to display graphical indication 5054 afterinitialization of the navigation system 10 and before or after thecalibration process is completed. Additionally, the processor system 12can be configured to remove or not display a graphical representation ofthe implantable device 30 when the device is flipped over or inverted toaide in drawing the user's attention to the flipped over or invertedstatus, as also shown in FIG. 17.

The processor system 12 can cooperate with the localizer 22 to providecalibrated guidance zones or areas, such as a first or general guidancezone or area 5064 and a second or detailed guidance zone or area 5068,as shown in FIG. 1. The general guidance area 5064 can include an 8-16inch (203.2-406.4 mm) diameter or range centered around the target port32 or implantable device 30, and the detailed guidance area 5068 caninclude a 4-8 inch (101.6-203.2 mm) diameter or range also centeredaround the target port 32 or implantable device 30. The navigationsystem can be configured to determine when the tracked instrument 61,61″ is in one of the areas 5064, 5068, and provide general and detailedguidance information, respectively, as will be discussed in greaterdetail below. It should be appreciated that the above dimensions for theguidance areas can be varied as may be desired, for example, inconnection with different implantable device configurations, localizerconfigurations, and/or patient sizes.

After the navigation system has been initialized, in a scenario wherethe implantable device 30 is not inverted or the inverted condition hasbeen diagnosed, the navigation system 10 can prompt the user via displaydevice 14 to select a needle 4058 and input a selected needle length viaa keyboard or other input device coupled to the processor system 12 anddisplay device 14. The user can then position the tracked instrument 61,61″ in the general area identified by the palpation and observe theimage area 5010 for guidance information. For discussion purposes, ascenario where the user initially positions the tracked instrument 61,61″ in the general guidance area 5064 will be discussed.

In this scenario, the processor system 12 is configured to determinethat the tracked instrument 61, 61″ is within the general guidance area5064, but outside of area 5068 where specific guidance information canbe displayed. General guidance information, such as a directionalindicator 5072, can be displayed on the image area 5010 to provide ageneral indication of a direction to move the tracked instrument 61, 61″toward the target port 32 and thus the area of detailed guidanceinformation 5068. As can be seen in FIG. 19, the directional indicator5072 can be in the form of an arrow illustrating to the user the generaldirection to move the tracked instrument 61, 61″. However, it should beappreciated that the direction indicator 5072 can be illustrated invarious forms sufficient to identify a general direction for guiding ornavigating the tracked instrument 61, 61″.

As the user moves the tracked instrument 61, 61″ in the generaldirection of directional indicator 5072, the processor system 12 can beconfigured to display detailed guidance information 5076 on the imagearea 5010 when the tracked instrument is positioned in or enters thedetailed guidance area 5068, as generally shown for example in FIGS. 20and 21. It should be appreciated that a user can initially position thetracked instrument 61, 61″ in the detailed guidance area 5068 where thedetailed guidance information 5076 can be displayed without previouslydisplaying the general guidance information or directional indicator5072.

With particular reference to FIGS. 20-23, the detailed guidanceinformation 5076 can be displayed in the form of multiple two orthree-dimensional guidance rings 5080. The guidance rings 5080 can be aseries of two or three-dimensional rings spaced apart a fixed distance.The guidance rings 5080 can be configured to display a location andorientation of the tracked instrument 61, 61″ relative to the targetport 32, as well as a distance of a distal tip 4059 of the needle 4058relative to the target port 32, as will be discussed below in greaterdetail. The guidance rings 5080 can be positioned around a longitudinalaxis 5084 and orientated perpendicular to a directional vector of thetracked instrument 61, 61″, which can be parallel to the longitudinalaxis 5084, as shown in FIG. 21. The guidance rings 5080 can be displayedin the form of three rings—a first ring 5092, a second or middle ring5096, and a third ring 6000.

A diameter of each ring can be successively larger from the first ring5092 to the third ring 5094 so as to form an overall conical shape orform 6002, as shown for example in FIG. 22. Each ring of the guidancerings 5080 can be displayed in a different color on the image area 5010to facilitate distinguishing the displayed rings from each other. Itshould be appreciated that while the drawings illustrate patternsassociated with the guidance rings 5080, these patterns are for drawingillustration purposes and are used to designate different colors beingassociated with the rings. Such patterns are not necessary for use incombination with the guidance rings 5080 being displayed with differentcolors, but may be used in place of colored rings on, for example, ablack and white display system. It should also be appreciated that moreor less guidance rings can be used to provide the detailed guidanceinformation, as well as different shapes in place of the rings withoutdeparting from the spirit or scope of the present disclosure.

The guidance rings 5080 can be displayed spaced apart from each other soas to have an overall length 6004 (FIG. 21) that can be scaled to adistance of the selected needle length, or to a predetermined spacedapart relationship if a needle length has not been selected. In thisregard, the first ring 5092 can indicate where the distal tip 4059 ofneedle 4058 would intersect a point on the implantable device 30 (i.e.,a location of the distal tip 4059 relative to the implantable device 30)and the third ring 6000 can indicate the distance or selected needlelength 6004 from where the needle would intersect the implantable device30. The processor system 12 can also be configured to display anadditional ring 6008 indicative of a current position of the distal tip4059 of the selected needle 4058 relative to the selected target port 32of the implantable device 30. In this regard, when the user places thetracked instrument 61, 61″ on or immediately adjacent to the skin ofpatient 16, the processor system 12 can determine the position of thetracked instrument 61, 61″ relative to an entrance of target port 32 anddetermine if the selected needle length is long enough to extend througha distance from the outer skin surface of patient 16 to the portentrance.

As one of ordinary skill in the art can appreciate, exemplary patient 16could have various levels of obesity such that while the user caninitially attempt to determine an approximate needle length by palpatingthe area, a verification that the initially selected needle length wouldreach the implantable device can be beneficial. In this regard, theprocessor system 12 can be configured to display ring 6008 relative toguidance rings 5080 to provide a visual indication regarding whether theselected needle length is long enough to reach the target port 32. Morespecifically, when the user places tracked instrument 61, 61″ on theskin of patient 16, the ring 6008 can be displayed between the first andthird concentric rings 5092, 6000 if the selected needle length is longenough to reach target port 32. If the processor system 12 determinesthat the selected needle length is not long enough to reach target port32, then ring 6008 can be placed outside and beyond the third ring 6000such that it would have a larger diameter than ring 6000, as shown forexample in FIG. 22.

The processor system 12 can be further configured to display a graphicalindication 6012 in the form of a numerical distance from the distal tip4059 of the selected needle 4058 to the entrance of target port 32, asshown for example in FIGS. 20 and 23. Graphical indication 6012 can bedisplayed when the tracked instrument 61, 61″ is in either the generalguidance area 5064 or the detailed guidance area 5068, as shown forexample in FIGS. 19 and 20, respectively. In addition, the graphicalindication 6012 can also be used to provide an additional or alternativeindication to the user regarding whether the selected needle length islong enough to reach target port 32. In this regard, the user canposition tracked instrument 61, 61″ on or immediately adjacent to theskin of patient 16 such that its location and trajectory are alignedwith target port 32, as shown in FIG. 23. If the tracked instrument 61,61″ includes the support tool 60, the tool can be placed directly on theskin in the above position. Alternatively, if the tracked instrument 61″is used without the support tool 60, the distal tip 4059 of the needle4058 can be placed immediately adjacent to the skin in the aboveposition. With either of the tracked instruments 61, 61″ in the aboveposition, the user can then read the distance to port numericalindication 6012 to identify a required needle length or to provideanother indication that the selected needle length is long enough toreach port 32. For example and with reference to FIG. 23, if theselected needle length is smaller than the displayed distance of 15.14mm, then the needle 4058 will not be long enough to reach target port32.

As discussed above, the graphical indication 6012 can be used incombination with ring 6008 or as an alternative to ring 6008. In theexemplary configuration shown in FIGS. 20 and 23, the graphicalindication 6012 is shown in combination with ring 6008, where it can beseen that the selected needle length is long enough based on ring 6008being smaller than third ring 6000 and between the first and third rings5092, 6000. If the selected needle length is determined not to be longenough, as shown in FIG. 22, then the user can select a longer needle,enter the newly selected needle length, and the navigation system candisplay ring 6008 relative to the guidance rings 5080 to provide thevisual indication regarding whether the newly selected needle lengthwill be long enough to reach target port 32.

In an alternative configuration, the processor system 12 can be operableto automatically determine a required length of the needle 4058 to reachthe target port 32 without first prompting the user to select a needle4058 and input an initial needle length, as discussed above. In thisregard, the user can place the tracked instrument 61, 61″ on the skin ofthe patient and align the location and trajectory of the trackedinstrument 61, 61″ with the target port, as will be described in moredetail below. Once aligned, the processor system 12 can automaticallydetermine the required needle length to reach target port 32 and can beoperable to cause the display device 14 to graphically render a requiredneedle length and/or product code or descriptor indicative of a certainneedle 4058 with the required length to be selected by the user.

The processor system 12 can be operable to display ring 6008 relative tothe first and third rings 5092, 6000 once the processor system 12 hasdetermined the required needle length in this alternative configuration.Additionally, the processor system 12 can maintain a database includinga list of preconfigured needles 4058 having various lengths and can beoperable to select a specific needle from the list upon determining therequired needle length as described above. In this regard, if thedetermined needle length is between two available needle lengthconfigurations stored in the list, the processor system can be operableto select the needle 4058 with the longer length to be communicated tothe display device 14 as described above.

With the tracked instrument 61, 61″ positioned in the detailed guidancearea 5068 such that the detailed guidance information 5076 is displayed,the user can align an insertion trajectory of the tracked instrument 61,61″ with the axis X of target port 32. If the tracked instrument 61 isused, the trackable support tool 60 can be manipulated about an outersurface of patient 16 such that the insertion trajectory or axis X″ ofsupport tool 60 aligns with axis X of target port 32. On the other hand,if the trackable supply assembly 50 with removably coupled trackingdevice 20″ is being used without the support tool 60, the insertiontrajectory or axis X′ of the needle 4058 can be aligned with the axis Xof target port 32.

The processor system 12 can be configured to display a trajectory orangular relationship of the longitudinal axis 5084 of guidance rings5080 relative to the axis X of target port 32, as shown for example inFIGS. 20 and 23. When the insertion trajectory or axis (X′ or X″) oftracked instrument 61, 61″ is not in alignment with the axis X of targetport 32 (which is parallel to the view direction or perpendicular to thetwo-dimensional image view of FIGS. 20-23), the guidance rings5092-6000, as well as ring 6008 (if a needle length has been selected),can be shown in a non-concentric relationship relative to an axisparallel to axis X of target port 32, as shown in FIGS. 20-22. Suchnon-concentric illustration of guidance rings 5092-6000 can indicate tothe user that the insertion trajectory of the tracked instrument 61, 61″and axis X of target port 32 are not aligned, as shown for example inFIG. 20. In addition, the processor system 12 can be configured to alsodisplay a graphical indication 6016 indicative of an angularrelationship between the axis of the tracked instrument 61, 61″ and axisX of target port 32. Graphical indication 6016 can, for example, includea numerical value of an angular offset between axis X of target port 32and the axis or insertion trajectory of tracked instrument 61, 61″, suchas the “ANGLE TO PORT: 22.00 degrees” indication illustrated in FIG. 20.

Using the guidance rings 5080 and/or the graphical indication 6016, theuser can manipulate the orientation of the trajectory of trackedinstrument 61, 61″ such that the longitudinal axis or insertiontrajectory of tracked instrument 61, 61″ (i.e., X′ or X″), and thus thelongitudinal axis 5084 of guidance rings 5080, are parallel to axis X oftarget port 32. In this manner, the user can observe the display ofguidance rings 5080 and manipulate the tracked instrument 61, 61″ suchthat guidance rings 5080 form a concentric or bull's eye pattern 6020about an axis parallel axis X of target port 32, as shown in FIG. 23.The concentric pattern 6020 can provide a visual indication that therespective axis of tracked instrument 61, 61″ is in parallel alignmentwith axis X of target port 32. While FIG. 23 illustrates guidance rings5080 in a concentric pattern over or surrounding the target location5032, it should be appreciated that the trajectory of tracked instrument61, 61″ can be aligned with axis X of target port 32 when in a locationnot over or away from target location 5032. It should also beappreciated that longitudinal axis 5084 is shown for discussion purposesand is not required to display the trajectory of tracked instrument 61,61″.

As discussed above, the processor system 12 can be configured to displaya location of tracked instrument 61, 61″ relative to target port 32 ofthe implantable device 30. In this regard, the user can move or navigatetracked instrument 61, 61″ relative to the skin of patient 16 so as toplace the first ring 5092 of the guidance rings 5080 over the graphicalrendering of cross-hair target location 5032, as shown in FIG. 23.Having the first ring 5092 surrounding target location 5032 of targetport 32 can provide visual confirmation to the user that at least adistal end of the selected needle 4058 of the tracked instrument 61, 61″is over or above target port 32. If the trajectory of tracked instrument61, 61″ has already been aligned with axis X of target port 32, then theguidance rings 5080 can be concentric about an axis parallel to axis Xof target port 32 and surrounding target location 5032, as shown forexample in FIG. 23.

However, it should be appreciated that the location of trackedinstrument 61, 61″ can be positioned over target port 32 without firstaligning the trajectory of tracked instrument 61, 61″ with axis X oftarget port 32, as shown for example in FIG. 21. In this scenario, thefirst ring 5092 can be positioned over target location 5032, but theremaining guidance rings 5096 and 6000 will not be concentricallyaligned with first ring 5092, thus indicating that the trajectory of thetracked instrument 61, 61″ and axis X of port 32 are not aligned. Inthis case, the trajectory of the tracked instrument 61, 61″ can then bealigned with axis X of target port 32 such that the guidance rings 5080can be concentrically located around target location 5032, as shown inFIG. 23.

Once both the location and the trajectory of the tracked instrument 61,61″ are aligned with target port 32, the processor system 12 can beconfigured to provide a graphical indication 6024 in image area 5070confirming the location and trajectory of tracked instrument 61, 61″ arealigned with target port 32 such that the needle 4058 can then beinserted into target port 32. In one aspect of the present teachings,graphical indication 6024 can be in the form of a prompt 6028 on imagearea 5070 that displays “INSERT NEEDLE” as shown in FIG. 23.

With reference to FIGS. 1, 20-21 and 23, insertion of needle 4058 intotarget port 32 will now be discussed in greater detail. With referenceto tracked instrument 61″ having the trackable supply assembly 50 withremovably coupled tracking device 20″, once the trajectory and locationof tracked instrument 61″ are aligned as discussed above, the needle4058 can be inserted into patient 16 and into target port 32. As theneedle 4058 is being inserted, a distance from the distal tip 4059 ofthe needle 4058 to the target port 32 continually decreases until distaltip 4059 reaches and enters target port 32. During such insertion, theprocessor system 12 can be configured to track a position of distal tip4059 relative to target port 32 when the tracked instrument 61″ isutilized, as the tracking device 20″ moves with needle 4058 duringinsertion of the needle. In this manner, ring 6008 can move along thelongitudinal axis 5084 of guidance rings 5080 during insertion of needle4058 from an initial position where the distal tip 4059 is adjacent theskin of patient 16 towards the first ring 5092, which is indicative of aposition within patient 16 at which the distal tip 4059 of needle 4058can intersect target port 32.

As ring 6008 moves towards first ring 5092, the diameter of ring 6008can progressively decrease proportionally to the conical form 6002 ofguidance rings 5080 such that as ring 6008 reaches first ring 5092, itcan have the same or substantially the same diameter as first ring 5092.In this manner, when the guidance rings 5080 are concentrically alignedover target location 5032 as shown in FIG. 23, the progressivelydecreasing diameter of ring 6008 during the needle insertion process canprovide a visual indication of the proximity to the entrance of targetport 32. When ring 6002 reaches the same depth as first ring 5092, whichcan be signified by having the same diameter in a concentric pattern ofthe rings, the distal tip 4059 of needle 4058 can be at the entrance totarget port 32.

If the support tool 60 is used with the non-trackable supply assembly 50(i.e., without the tracking device 20″ coupled thereto), the navigationsystem 10 can be configured to also display ring 6008 relative to theguidance rings 5080 to provide the above-discussed visual feedbackregarding whether the selected needle length is long enough to reachtarget port 32. However, as the tracking device 20 in support tool 60can be fixed relative to the tool, it does not move in thisconfiguration along with the needle 4058 when it is being inserted. Inthis aspect of the present teachings, ring 6008 can remain stationaryduring insertion of needle 4058.

The processor system 12 can also be configured to provide feedback thatthe needle 4058 has been successfully inserted into target port 32. Inone aspect of the present teachings, the implantable device 30 caninclude a sensor, such as a transducer 6032, associated with target port32 such that when the distal tip 4059 of needle 4058 is receivedtherein, a graphical indicator 6036 can be displayed to provideconfirmation that needle 4058 has been inserted into target port 32. Thetransducer 6032 can also be configured to not only provide confirmationthat the target port 32 has been reached by needle 4058, but also thatthe needle 4058 has been inserted into target port 32 to a predetermineddepth sufficient for delivery of the functional fluid to reservoir 34. Awireless link can be established between the implantable device 30 andthe processor system 12 to facilitate communication therebetween.

Turning now to FIG. 24, a logic block diagram illustrating an exemplarymethod or procedure for utilizing the navigation system 10 having theimplantable device 30 and tracked instrument 61, 61″ is illustrated infurther detail. As generally discussed above in connection with thesystem for displaying guidance information, the procedure can includepalpating patient 16 at block 6050 to determine a general location ofthe implantable device 30, as well as a general indication of a needlelength than can be required to reach the implantable device 30. Thenavigation system 10 can be initialized at block 6052 and then the usercan proceed to select the implantable device model at block 6054 that isassociated with patient 16 from a preconfigured menu or databaseassociated with processor system 12. It should be appreciated that whileFIG. 24 illustrates initializing the navigation system 10 afterdetermining the general location of implantable device 30, theseprocedures could be carried out concurrently or in a reverse order. Inaddition, the navigation system can be initialized via data communicatedvia the telemetry system and the implantable device model associatedwith patient 16 can be automatically determined by the data sent via thetelemetry system. In this alternative configuration, the procedure cancontinue along phantom line 6053 from block 6052 to block 6056.

Upon selection of the implantable device model (or receiving dataidentifying the model), the procedure can continue to the calibrationprocess described above and referenced at block 6056. Upon completingthe calibration process, the navigation system can be configured toidentify whether the flipped pump condition exists at block 6058. Itshould again be appreciated that while the flipped pump conditiondetermination is illustrated after the calibration process block 6056,the navigation system 10 can be configured to determine whether theflipped pump condition exists concurrently with or before thecalibration process. If the flipped pump condition is identified, theprocedure can continue with diagnosing the flipped pump condition atblock 6060. If the flipped pump condition is not identified by thenavigation system 10, then the procedure can continue to block 6062where the user can be prompted to select the target port, such as port32 discussed above, if the selected implantable device model includesmore than one port configured to receive a functional fluid or the like.It should be appreciated that it may not be necessary to select thetarget port if, for example, the selected implantable device modelincludes only one applicable port for receiving the functional fluid.

The procedure can continue to block 6064 where the needle length can beselected and the selected length communicated to the processor system12. The user can be requested to enter the needle length via the promptdisplayed in the image area 5010, as discussed above. With the needlelength selected, the procedure can continue to block 6068 where thetracked instrument 61, 61″ can be placed on or adjacent to the skin ofpatient 16 in the general area determined in block 6050. Uponpositioning the tracked instrument 61, 61″ in this area, the user canobserve the image area 5010 for guidance information to align and locatethe tracked instrument relative to the target port 32 of the implantabledevice 30. In an alternative configuration where the processor system 12is operable to automatically select the required needle length once thetracked instrument 61, 61″ is aligned with the target port, theprocedure can bypass block 6064 and continue from block 6062 alongphantom line 6065 to block 6070.

Depending on where the tracked instrument is initially positionedrelative to the general and detailed guidance areas, the user mayobserve general directional indicator 5072 or detailed guidanceinformation 5076 if the tracked instrument 61, 61″ is positioned indetailed guidance area 5068. Additionally, it is possible that neitherthe general or detailed guidance information can be displayed if thetracked instrument 61, 61″ is initially positioned outside the generalguidance area 5064. If general guidance information is displayed atdecision block 6070, such as the directional indicator 5072, the usercan move the tracked instrument in the direction indicated bydirectional indicator 5072 until the detailed guidance information 5076is displayed, as noted in block 6072.

With the detailed guidance information being displayed, the procedurecan continue to decision block 6074 where the user can determine if theselected needle length is long enough to reach the target port 32. Asdiscussed above, the user can determine if the selected needle length isof sufficient length to reach target port 32 through use of ring 6008and/or graphical indicator 6012, and if not, select a longer needle asnoted in block 6076. In addition, as also discussed above, it should beappreciated that the determination regarding the selected needle lengthcan be performed at various times throughout the procedure, includingafter the tracked instrument 61, 61″ has been located and alignedrelative to target port 32.

The procedure can continue to block 6078 where the trajectory of thetracked instrument 61, 61″ can be aligned with axis X of target port 32.With the trajectory aligned, the tracked instrument 61, 61″ can betranslated until first ring 5092 is located over target port 32 suchthat the graphical representation of target location 5032 is encompassedby first ring 5092, as referenced in block 6080.

In the alternative configuration where the processor system 12 isoperable to automatically determine the required needle length to reachthe target port 32, the procedure can bypass blocks 6074 and 6076 andcontinue from block 6070 to block 6078 along phantom line 6077. In thisconfiguration, the procedure can continue from block 6080 to block 6081where the processor can automatically determine a required needle lengthfor the tracked instrument 61 or 61″ to reach target port 32.

The procedure can then continue to block 6082 where graphical indicator6024 can be displayed to instruct the user to insert needle 4058 intotarget port 32. The needle 4058 can then be inserted at block 6084 and aconfirmation can be displayed at block 6086 indicating that the needle4058 has been received in target port 32. At this point, the reservoircan be filled with the functional fluid and the needle 4058 can then beremoved from the target port 32.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

1. A system for generating a field relative to an implanted medicaldevice, comprising: a coil array positioned in the implanted medicaldevice including a plurality of coils each having a winding group formedon a flexible circuit; a single power source in the implanted medicaldevice to power all components of the implanted medical device includingthe coil array; and a processor operable to energize the coil arrayaccording to selected instructions to assist in providing asubstantially constant amplitude alternating current and/or voltage tothe coil array; wherein each of the plurality of coils in the coil arrayis formed substantially thin in the flexible circuit to provide asubstantially thin profile of the flexible circuit.
 2. The system ofclaim 1, wherein the plurality of coils includes three coils and thewinding group include three winding groups; wherein each of the threewinding groups includes a first winding portion separated from a secondwinding portion by an isolation layer; wherein the first winding portionand the second winding portion are operable as a single coil having aselected total number of windings.
 3. The system of claim 2, wherein thefirst winding portion and the second winding portion of each of thethree winding groups includes substantially identical number of turns ofa conductive material.
 4. The system of claim 3, wherein the firstwinding is formed on a first layer of material and the second winding isformed on a second layer of material separate from the first layer. 5.The system of claim 4, wherein the implanted medical device has a port;wherein all of the three coils are spaced apart around the port.
 6. Thesystem of claim 1, a tuning capacitor having a capacitance to maximizecurrent through the coil array.
 7. The system of claim 1, furthercomprising: a pump operable to pump a functional material from areservoir in the implanted medical device; and a telemetry systemoperable to transmit and receive data regarding the implanted medicaldevice; wherein the pump and the telemetry system are components of theimplanted medical device powered by the single power source.
 8. Thesystem of claim 6, further comprising: a receiving coil array in atracking device; a support member including a three dimensionallycontoured nesting surface that conforms to a corresponding threedimensionally contoured surface of a supply assembly, the correspondingsurface of the supply assembly nesting against the nesting surface tosupport the supply assembly such that the supply axis remainssubstantially fixed relative to and aligned with the support axis,wherein the support member houses the tracking device; and a displayoperable to display with annular ring icons the location of the supportmember relative to the implanted medical device.
 9. The system of claim6, further comprising: a first tuning capacitor and a second tuningcapacitor and a switch; wherein the switch is operable to switch thecircuit to connect at least one coil of the plurality of coils in thecoil array to tune to a selected frequency the circuit that includes theselected tuning capacitor and the at least one coil.
 10. The system ofclaim 6, further comprising: an operational amplifier having an inputvoltage and outputting a reference voltage based on the input voltage; afirst PMOS cascode, a second PMOS cascode, and a NMOS current mirrorreceiving the output from the operational amplifier; a tuning capacitorhaving a capacitance variance over a selected lifespan of less thanabout 3% and in parallel with the plurality of coils of the coil array;and a switch to switch the output from the second PMOS cascode to theparallel tuning capacitor and at least one of the plurality of coils.11. A method of operating a localizer associated with an implantedmedical device having a single power source to generate a navigationfield and transmit telemetry from the implanted medical device, themethod comprising: operating the implanted medical device to deliver atherapy to a patient including drawing a current from the single powersource; sending a stop signal to a receiver in the implanted medicaldevice to stop the operation of the implanted medical device fromdelivering the therapy; in response to the stop signal, stopping theoperation of the implanted medical device from delivering the therapy;after stopping operation of the implanted medical device from deliveringthe therapy, starting a port finder routine having sub-routinesincluding starting a port finder timer to time the operation of the portfinder routine; powering a coil to emit a field; determining whether theport finder timer has expired; when it is determined that the portfinder timer has expired, restarting the operation of the implantedmedical device to deliver the therapy.
 12. The method of claim 11,wherein powering a coil includes powering at least a first coil and asecond coil, and further comprising: starting a gap timer after poweringthe first coil and prior to powering the second coil; after powering thesecond coil, starting a blank time; wherein during the gap timer andduring the blank timer neither of the first coil, nor the second coilare powered.
 13. The method of claim 12, wherein the length of the gaptimer and the length of the blank timer are different.
 14. The method ofclaim 13, determining with a navigation processor the identification ofthe first coil or the second coil being powered based on the length ofthe gap timer or the blank timer.
 15. The method of claim 14, furthercomprising: sensing a first field emitted by the first coil with anantenna; sensing a second field emitted by the second coil with theantenna; and determining a location information of the antenna based onthe sensed first field and the sensed second field.
 16. The method ofclaim 15, further comprising: powering a third coil to emit a thirdfield; and sensing the third field with the antenna; wherein determiningthe location of the antenna is based on sensing all of the first field,the second field, and the third field.
 17. The method of claim 11,further comprising: transmitting or receiving telemetry information withthe coil if the port finder timer has expired.
 18. A system to provide aconstant amplitude alternating current and/or voltage to a localizer inan implanted medical device, comprising: an operational amplifieroperable to receive an input voltage and output a reference voltage to aprecision resistor and a first PMOS current mirror cascode; a NMOScurrent mirror operable to receive an output voltage from the precisionresistor; a second PMOS current mirror cascode operable to receive anoutput voltage from the NMOS current mirror and the first PMOS currentmirror cascode to output a substantially constant amplitude alternatingcurrent and/or voltage based on the output reference voltage; a firstcoil; a first capacitor; and a first switch to form a connection betweenthe second PMOS current mirror cascode and the first coil and the firstcapacitor; wherein the first capacitor is operable to tune the frequencyof the output from the first coil to a selected frequency.
 19. Thesystem of claim 18, further comprising: a second coil, a secondcapacitor, and a second switch; and a third coil, a third capacitor, anda third switch; wherein the first switch, the second switch, and thethird switch are alternatively activated to energize the respectivefirst coil and first capacitor, the second coil and the secondcapacitor, and the third coil and the third capacitor.
 20. The system ofclaim 19, wherein the first capacitor with the first coil, the secondcapacitor with the second coil, and the third capacitor with the thirdcoil are operable to tune an oscillation through the respective coil andcapacitor circuits to a selected frequency.
 21. The system of claim 20,wherein the constant amplitude alternating current and/or voltage variesless than about 1%.
 22. The system of claim 20, further comprising: afirst PMOS input signal to the first switch to activate the firstswitch; a second PMOS input signal to the second switch to activate thesecond switch; and a third PMOS input signal to the third switch toactivate the third switch; wherein the first PMOS input signal, thesecond PMOS input signal, and the third PMOS input signal are generatedto alternatively activate the first switch, the second switch, and thethird switch.
 23. A system for generating a field relative to animplanted medical device, comprising: a coil array positioned in theimplanted medical device including a single coil or a plurality of coilseach having a winding group formed on a circuit; a power source in theimplanted medical device to power all components of the implantedmedical device including the coil array; and a processor operable toenergize the coil array according to selected instructions to assist inproviding a current to the coil array; wherein each of the plurality ofcoils in the coil array is formed substantially thin in the flexiblecircuit to provide a substantially thin profile of the flexible circuit.24. The system of claim 23, wherein the coil array is formed on aflexible circuit; wherein the power source is a single power source inthe implanted medical device to power all components of the implantedmedical device including the coil array; and wherein the processor isoperable to energize the coil array according to selected instructionsto assist in providing a substantially constant amplitude alternatingcurrent to the coil array.
 25. The system of claim 24, wherein each ofthe single coil or the plurality of coils in the coil array is formedsubstantially thin in the flexible circuit to provide a substantiallythin profile of the flexible circuit.
 26. The system of claim 23,wherein the plurality of coils includes three coils and the windinggroup include three winding groups; wherein each of the three windinggroups includes a first winding portion separated from a second windingportion by an isolation layer; wherein the first winding portion and thesecond winding portion are operable as a single coil having a selectedtotal number of windings.
 27. The system of claim 26, wherein the firstwinding portion and the second winding portion of each of the threewinding groups includes substantially identical number of turns of aconductive material.
 28. The system of claim 26, wherein the firstwinding is formed on a first layer of material and the second winding isformed on a second layer of material separate from the first layer. 29.The system of claim 26, wherein the implanted medical device has a port;wherein all of the single coil or the plurality of coils are spacedapart around the port.
 30. The system of claim 26, wherein each of thewinding portions are substantially ovoid in shape.
 31. The system ofclaim 26, further comprising: a pump operable to pump a functionalmaterial from a reservoir in the implanted medical device; and atelemetry system operable to transmit and receive data regarding theimplanted medical device; wherein the pump and the telemetry system arecomponents of the implanted medical device powered by the single powersource.
 32. The system of claim 23, further comprising: a receiving coilarray in a tracking device; a support member including a threedimensionally contoured nesting surface that conforms to a correspondingthree dimensionally contoured surface of a supply assembly, thecorresponding surface of the supply assembly nesting against the nestingsurface to support the supply assembly such that the supply axis remainssubstantially fixed relative to and aligned with the support axis,wherein the support member houses the tracking device; and a displayoperable to display with annular ring icons the location of the supportmember relative to the implanted medical device.
 33. The system of claim23, further comprising: a first tuning capacitor and a second tuningcapacitor and a switch; wherein the switch is operable to switch thecircuit to connect at least one coil of the plurality of coils in thecoil array to tune to a selected frequency the circuit that includes theselected tuning capacitor and the at least one coil.
 34. The system ofclaim 23, further comprising: an operational amplifier having an inputvoltage and outputting a reference voltage based on the input voltage; afirst PMOS cascode, a second PMOS cascode, and a NMOS current mirrorreceiving the output from the operational amplifier; a tuning capacitorin parallel with the plurality of coils of the coil array; a switch toswitch the output from the second PMOS cascode to the parallel tuningcapacitor and at least one of the plurality of coils.
 35. A system forreceiving a field within an implanted medical device, comprising: a coilarray positioned in the implanted medical device including a single coilor plurality of coils each having a winding group formed on a circuit; apower source in the implanted medical device to power all components ofthe implanted medical device; a processor operable to measure thesignals from a received field according to selected instructions andgenerate data regarding the measured signals; and a telemetry processingsystem operable to receive the generated data regarding the measuredsignals to an external processor system; wherein the external processorsystem is operable to determine a location of an emitting system that isemitting the received field.
 36. A method of operating a localizerassociated with an implanted medical device having a power source togenerate a navigation field and transmit telemetry from the implantedmedical device, the method comprising: operating the implanted medicaldevice to deliver a therapy to a patient including drawing a currentfrom the single power source; sending a stop signal to a receiver in theimplanted medical device to stop the operation of the implanted medicaldevice from delivering the therapy; in response to the stop signal,stopping the operation of the implanted medical device from deliveringthe therapy; after stopping operation of the implanted medical devicefrom delivering the therapy, starting a port finder routine havingsub-routines including starting a port finder timer to time theoperation of the port finder routine; powering a coil to emit a field;determining whether the port finder timer has expired; when it isdetermined that the port finder timer has expired, restarting theoperation of the implanted medical device to deliver the therapy. 37.The method of claim 36, further comprising: providing only a singlepower source within the implanted medical device.
 38. The method ofclaim 36, further comprising: emitting a field with an antenna systemexternal to the implanted medical device; sensing the field with thecoil; and determining the location of the antenna based on the sensedfield; wherein the coil can include more than one coil and the antennacan include more than one field emitting portion to allow determinationof multiple degrees of freedom location information of the antennarelative to the implanted medical device.
 39. The method of claim 36,wherein powering a coil includes powering at least a first coil and asecond coil, and further comprising: starting a gap timer after poweringthe first coil and prior to powering the second coil; after powering thesecond coil, starting a blank time; wherein during the gap timer andduring the blank timer neither of the first coil, nor the second coilare powered.
 40. The method of claim 39, wherein the length of the gaptimer and the length of the blank timer are different.
 41. The method ofclaim 40, determining with a navigation processor the identification ofthe first coil or the second coil being powered based on the length ofthe gap timer or the blank timer.
 42. The method of claim 41, furthercomprising: sensing a first field emitted by the first coil with anantenna; sensing a second field emitted by the second coil with theantenna; and determining a location information of the antenna based onthe sensed first field and the sensed second field.
 43. The method ofclaim 42, further comprising: powering a third coil to emit a thirdfield; and sensing the third field with the antenna; wherein determiningthe location of the antenna is based on sensing all of the first field,the second field, and the third field.
 44. The method of claim 40,determining with a navigation processor the identification of the firstcoil or the second coil and ordering the first coil or the second coilbeing sensed at a selected time based upon the length of a gap time or ablank time.
 45. The method of claim 36, further comprising: transmittingor receiving telemetry information with the coil if the port findertimer has expired.